The Baths of Diocletian

  • Elisabeth Eckardt - Faculty of Behavioural and Social Sciences
  • Vivian Fafié - Faculty of Economics and Business
  • Sjoukje Reijenga - Faculty of Behavioural and Social Sciences

The Baths of Diocletian [1]

The Santa Maria degli Angeli e dei Martiri (further reading), located nearby the Piazza della Repubblica, is definitely worth a visit when in Rome. It is an enormous church which consists of several noteworthy remainders from ancient times. This place reveals plenty of history, because it contains multiple historical aspects from the original Baths of Diocletian. Although there is relatively little left of the original Baths of Diocletian, the remainders of it have survived many centuries. During these centuries, the purpose(s) of the complex has changed, although several parts of the Bath complex remained original over time. In this Wiki, the history of the Baths of Diocletian will be examined. This way, not only new insights on the historical purposes of the Baths are provided, but also insights into the current purposes of this complex.

Nowadays, the complex is not used for bathing anymore. However, when investigating the building carefully, many historical aspects can still be found. In order to be able to examine the purposes of the complex, a deeper dive into the baths and its history is required to acquire knowledge beyond the generally available information.

In the following paragraphs, different aspects of the bath complex will be considered to put the background history, contemporary happenings during the construction, and future implications of the Baths into context. This detailed examination results in several questions, which will be suggestively answered throughout the Wiki.

The Baths of Diocletian around the 4th century [2]
1. Current purposes
1.1 The Baths of Diocletian as a church
1.2 The Baths of Diocletian as a museum
2. Details and surroundings of the Baths of Diocletian
2.1 General facts
2.2 Location of the Baths of Diocletian
3. General bathing culture
3.1 Comparison to other baths
4. Background and history
4.1 Historical facts and events
4.2 Diocletian
4.3 Maximian
5. Suggestions
5.1 ...for the size of the Baths
5.2 ...for the location of the Baths
5.3 ...for the current purpose of the Baths
6. Conclusion

Current purposes

The Baths of Diocletian as a church

3 4

It was not until 1560, during the reign of Pope Pius IV Medici (1559-1565), that the plans for renovating and making use of Diocletian's Baths were seriously considered and keenly debated. Pius IV heard of the wishes of Antonio del Duca and decided to undertake the project for converting the tepidarium of the Baths into a church dedicated to The Santa Maria degli Angeli e dei Martiri. Moreover, a Charterhouse needed to be attached to commemorate the Christian martyrs who, according to legend, died during the construction of the Baths. Its construction continued throughout the 17th century.

The pope delegated the task of commissioning and planning the church designs to Michelangelo. This famous architect used both the frigidarium and the tepidarium areas without altering the original structures. Furthermore, Michelangelo managed to use the original bases for the Baths' red porphyry columns, which means layers of different times exist in the Basilica. The small Cloister adjacent to the church's presbytery was also planned by Michelangelo. It occupies about a third of the original natatio's (swimming pool) surface.

The Baths of Diocletian as a museum

5 6

Besides the main church in the ancient frigidarium and tepidarium, part of the remainders of the complex are transformed into a museum; the Museo Nazionale Romano. This museum was instituted in 1889 and consists of four buildings: Crypta Balbi, Palazzo Massimo, the Baths of Diocletian and Palazzo Altemps. The part in the Baths of Diocletian contains two sections. First, an epigraphic section with one of the most important and richest epigraphic collection of the world with a holding of 10.000 inscriptions. The inscriptions show the course of the Roman civilization from the birth of the City of Rome to the fall of the Empire. Second, a pre-historic section which collects the archaeological testimonies of the most ancient stages of the culture from 11th-10th centuries to the early 6th century B.C. Besides these exhibitions, it is possible to have a stroll in Michelangelo's Cloister of the Charterhouse. Moreover, throughout the last decades an increasing number of old parts of the Baths of Diocletian have been restored and reopened to the public.

Details and surroundings of the Baths of Diocletian

General facts

1. Calidarium, 2. Tepidarium 3. Frigidarium
4. Natatio, 5. Palaestra, 6. Entrance, 7. Exedra [7]

The Baths of Diocletian were to become the largest complex of thermal baths anywhere throughout the Roman Empire, which could accommodate up to three thousand people. The construction of the Baths of Diocletian started in 298 A.D. and finished between 305 and 306 A.D. To build the bath complex, a large number of both private and public buildings were demolished. The Baths of Diocletian covered an area of more than 13 hectares (376 x 361 metres), with the main entrance at the north-eastern side and, in the middle of the opposite side, a large exedra (meeting rooms) with steps corresponding to today's piazza della Repubblica. On both sides of the exedra there were two libraries, flanked at the extremities by two circular halls; one of them was transformed in 1598 into the church of San Bernardo alle Terme, the other one is still visible at the beginning of Via del Viminale and serves nowadays as an entrance for a garage. The main halls, which were the frigidarium, the tepidarium, and the calidarium were aligned along a central axis; around this axis were placed, symmetrically, all the other halls. On the sides of the frigidarium were two large outdoor gymnasia, the western one of which is partially visible in the archeological area of Via Cernaia. Two octagon halls were aligned calidaria. One of these was used as a planetarium from 1928 till the 1980s. All together, the Baths of Diocletian must have looked like this in Antiquity.

Location of the Baths of Diocletian

The hills of Rome [8]

The Baths of Diocletian were built between the Viminalis and the Quirinalis hills. The city of Rome already knew a significant number of bathing complexes before the construction of the Baths of Diocletian. However, this latter bathing complex was the only one of this particular size located in the northern part of the city. The construction site was located within the oldest Roman defensive wall (Servian Wall) that were constructed in the 4th century B.C. as the hills of Quirinalis and Viminalis are against the northern border of these walls. The Baths of Trajan were located more towards the ancient city centre, whereas the Baths of Caracalla were not located within the Servian walls at all.

Besides the location in the city of Rome, the location in the Roman Empire has to be discussed. Diocletian is renowned for the division of the Roman Empire. With this division in mind, Rome is not located in Diocletian's district, but in his co-emperor Maximian's district. It is also interesting to note that this emperor was not seated in Rome as usual for earlier emperors. The location raises questions about the reasons for the construction at this particular site inside the city and this particular site in the Roman Empire.

General bathing culture

Bathing culture...[13] ancient Rome[15]

In Roman times, bathing portrayed a significant part of society and an essential element of civilized life. [10] The Roman city around the third century knew many bath complexes, such as the Baths of Trajan and the Baths of Caracalla, to only name the two largest before the Baths of Diocletian were inaugurated. Although wealthy Romans had baths in their own houses, it is assumed that most of the Roman population went to the public baths. A reason for this was that the baths were not only meant for washing and cleaning; the bath complexes of Ancient Rome enabled Roman inhabitants to communicate with each other and thus to socialize with other people from society. Besides bathing and relaxing, the baths provided opportunities for communication, contacts, business deals, and even courtship. [11] Thereby, the social aspect of the baths contributed to the feeling of being an involved member of Roman society. [12]

The bathing complexes existing around the third century comprised several different types of baths, which could typically be found in every bath complex. Among these baths were the frigidarium, calidarium, tepidarium, and a natatio. [14] Mostly, there were different entrances for women, men and sometimes even slaves. A bathing complex did not just consist of different types of baths. Visiting a bath complex back then meant much more than only going there for a bath, because such complexes included gymnasia where people were able to exercise, libraries, religious sanctuaries, resting places and gardens. For example in the palaestra, a kind of gymnasium, Romans practised their wrestling or boxing skills. This versatility, along with the social aspects, are the most likely reasons for Romans to attend the public baths.

Comparison to other baths

As previously mentioned, the two other major bath complexes in ancient Rome were much smaller than the Baths of Diocletian. Nonetheless, the construction of the latter complex seems to have been highly influenced by the Baths of Trajan and of Caracalla. Looking at the layout of all three bath complexes, it can easily be observed that especially the Baths of Trajan have a striking resemblance to the Baths of Diocletian in their design. This is not only due to external factors, such as the rectangle design of the halls and the semi-circular arch. Historical sources claim that the inner design was very similar in all of these complexes. [11]

It can be assumed that all the large bathing complexes shared the same concepts of combining the bathing culture with the recreational nature described above. Although there is no evidence that the Baths of Diocletian comprised libraries as well, it is a common belief among scholars that there were rooms designated in the complex to serve as a library. This belief roots in the fact that all other known bathing complexes provided their bathers with at least one library room. Additionally, all of them had gymnasia, differently tempered baths, meeting rooms, and so on.

The major difference between other bathing complexes and the ones of Diocletian therefore seems to be the sheer capacity of the latter. The remaining question is why the bathing complex was constructed with this particular size. There are multiple speculations about this. Some of the reasons may include the wish to impress, to show domination, to proof that all the changes which Diocletian pushed through in the Roman Empire would be the beginning of a new century of wealth, or to simply show the Roman people the power of the Tetrarchy. It could also be due to the sheer size of Rome back then, which is estimated to have reached a population of approximately 1 million inhabitants. [16] More of this will be discussed later on.

17 18 19

Background and history

It is easy to find general information about the size and location of the Baths of Diocletian. However, the previous paragraphs raise the following questions: why were the baths located at that particular site? And why did the baths need to become so enormous compared to other bath complexes? In order to be able to answer these questions, more background information and historical facts about the Roman Empire in the third century, the emperor Diocletian, and the financial and political systems are required.

Historical facts and events

The time period before the construction of the Baths of Diocletian is known for its difficulties as a result of invasion, plague, economic depression and civil war, also known as the Crisis of the Third Century. With the rise of emperor Diocletian this crisis came to an end. The Baths of Diocletian were constructed between 298 until 305-306 A.D. A restoration must have taken place sometime between the 4th and the 6th century, but historians do not agree about when exactly the restoration took place. After the inauguration, it was actively used until barbarians destroyed the aqueducts in 537, putting an end to the extensive use of water that a bathing complex needed. Following the fall of the Roman Empire, the Baths of Diocletian suffered a period of slow but inexorable decline, as did many other classical buildings, both public and private. Romans used material from the baths for new building projects and also built inside the bathing complex. However, right up until the Renaissance these vast thermal baths were still largely unaltered from their original state and of unrivalled fascination as a result. The great exedra and a considerable portion of the perimeter were still standing, the facade of the swimming pool survived in almost all its beauty, and the combined strength and grace of the Roman structures stood out clearly in the gardens of the more recent villas.


The division of the Roman Empire
during the Tetrarchy[26]

As the name suggests, the Baths of Diocletian are named after the emperor Diocletian. He was the emperor of the Roman empire from 284 until 305 and in his reign, he successfully changed the empire's structure and financial system. The most impacting change was from a sole emperor to two emperors, called a Dyarchy. This Dyarchy resulted in a division of the empire in East and West. Later, the Dyarchy turned into a Tetrarchy, where two emperors ruled in cooperation with two sub-emperors.

Diocletian was the last emperor before Christianity was implemented as an official religion in the Roman Empire. Diocletian is criticized by literature for being a Christian-hater, however it is also suggested that the origin of the harassment and extreme dislike of Christianity came from his co-emperor Maximian (further reading).[21] This sounds solid, since approximately 40.000 Christian slaves were used for the construction of the baths, commissioned by Maximian. However, Diocletian was the one that decided that all churches had to close down in 303. [22]

It is believed that Diocletian has only visited Rome once, which raises more questions to why the baths of Diocletian were built at this particular site and why he wanted Rome to remember him. Rome was situated in the Western part of the Empire, ruled by Diocletian’s companion Maximian. Since East and West were separated, this might be a reason why Diocletian visited Rome only once. Diocletian visited the city of Rome in 303 A.D., arguably to celebrate the twentieth anniversary of his reign, the tenth anniversary of the Tetrarchy and a triumph for the war with Persia. [23] Unexpectedly, he left the city of Rome earlier than planned, possibly because the inhabitants did not show enough deference towards his superiority.

During their reign, Maximian and Diocletian were both reluctant to visit Rome, and this resulted in a shift of centrality from Rome to other cities like Milan. This might be a reason for the fact that the inhabitants of Rome showed an aversion against the emperors by the time they visited Rome[24]. As mentioned, the Baths of Diocletian were commissioned by Maximian in honor of Diocletian by 298 A.D. This was a remarkable year because by then, Maximian returned from successful battles in Africa. Evidence for this was found in bricks of the baths. [23]



Maximian has played an important role during the reign of Diocletian and in the construction of the Baths of Diocletian. The relationship between Maximian and Diocletian was like a brotherhood and was based on loyalty. Possibly, the dedication of the Baths to Diocletian was a sign of this loyalty. This would mean that the whole construction, the location of the complex, and the use of the Christian slaves for the construction, was an incentive of Maximian.

Striking about the relationship between Maximian and Rome is that he failed to visit Rome frequently. After the victories in Africa in 296 A.D., he immediately visited Rome. [28]The signs in the bricks seem to confirm that the Baths of Diocletian commissioned the complex "on his return from Africa''. [29][28] This might provide interesting insights into the size and location of the baths. Did the complex have to do with loyalty, or with the great victory of Maximian in Africa? Or were the baths built to calm the unsatisfied inhabitants?


...for the size of the Baths

The information provided on the history, the emperors and the Roman Empire in this particular period reveal interesting subjects which possibly contribute to providing answers about the size and the location of the Baths of Diocletian. As stated, the Baths of Diocletian were the largest complex that ever existed throughout Roman history. Several reasons for the size could be argued. The most obvious reason for the enormous size is the status that the emperors Maximian and Diocletian wanted to convey to their audience. The size of the complex might have contributed to transferring the message of being dominant or impressive. A second reason for its size might be characterized by the financial crisis that played a huge role in the third century. Diocletian managed to change the financial system and thereby brought a new beginning; a new century of wealth. The Baths of Diocletian could have been a statement for the wealth and happiness to come, which symbolized the beginning of a new century of wealth towards Roman society.

Yet another reason could be the size of population of Rome in 300 A.D. Although the city lost some of its importance and therefore saw a decline in its population[31], it is still estimated to have been somewhere around 800.000. [32] The last reason which possibly contributes to the size of the Baths of Diocletian, is the establishment of the Tetrarchy. In this reasoning, the size of the complex might have contributed to conveying the fact that the power of the Tetrarchy around Diocletian was great, indeed much more powerful and impressive than a single emperor, and that altogether the Roman Empire was large.

...for the location of the Baths

Ancient Rome[33]

For this specific location, there are some possible reasons as well. One of them, as mentioned earlier, is that the Baths of Trajan and the Baths of Caracalla were located at other places in the city of Rome, one Southeast and one Southwest from the city, which meant that the Northern part of Rome was not yet provided with a bathing complex. Secondly, the Tetrarchy caused not only a division of power, but also a division of the Empire, since East and West were both ruled differently. The city of Rome in this time partially fell apart as well. The Baths of Diocletian might have been an expression towards society to create unity between East and West again, and consequently also inside Rome. Moreover, the Roman inhabitants lost their army, tax exemptions and legal privileges due to Diocletian's reformations. The bathing complex could have been constructed to satisfy them.

Altogether, there are multiple suggestions which can be concluded to answer the questions stated before. The history, emperors, and time of the reign reveal much about the Baths and their purposes, and therefore brought us closer to the bottom of the ancient waters of the Baths of Diocletian and the actual reasons for their construction.

...for the current purpose of the Baths

When reading about the use of Christian slaves, Diocletian and Maximian's aversion to Christians, and the current purpose of the Baths of Diocletian, one might discover a controversy. The Baths of Diocletian were commissioned by the last non-Christian emperors. Concluding from the way Christians were treated during their reign, Diocletian and Maximian had an aversion to Christians and approximately 40.000 Christian martyrs were used to construct the Baths of Diocletian. After a long period of time, a church was built in this particular bathing complex.

Considering the above, it is likely that the church was constructed deliberately in this particular building. The church was constructed as a dedication to the Christian martyrs who constructed the bathing complex, as stated in the inscription. It can be seen as a sign of forgiveness or revenge, but most importantly as an attempt to restore balance.


After analyzing the different aspects of the Baths of Diocletian, one might conclude that there is more to bathing complexes than just bathing for hygienic reasons and especially that there is more to constructing a building than just for its practical use. The Baths of Diocletian has shown itself to be a complex with many purposes throughout its existence. By serving these purposes, it became a building with different layers in time. It is also a complex which can convey many messages to its interested audience. Nevertheless, the reasons suggested in this text for the construction of the Baths of Diocletian will probably never be falsified or verified. However, with the evidence getting stronger and stronger every time you dive into the waters of the Baths of Diocletian in ancient times, you might eventually hit the bottom.


  1. Retrieved April 19, 2017 from Thermen
  2. Retrieved April 19, 2017 from Inside Picture
  3. Retrieved April 19, 2017 from Piazza
  4. Retrieved April 19,2017 from Church Inside
  5. Retrieved April 19, 2017 from Museum Outside
  6. Retrieved April 19, 2017 from Museum Inside
  7. Retrieved April 19, 2017 from Map of the Baths
  8. Retrieved April 19, 2017 from Hills of Rome
  9. Retrieved April 19, 2017 from Tetrarchy
  10. DeLaine, J. (1988). Recent research on Roman baths. Journal of Roman Archaeology, Cambridge UnivPress
  11. Dix, T. Keith (1994). Public Libraries in Ancient Rome, Libraries & Culture (University of Texas Press) 29 (3): 282-296, JSTOR 25542662
  12. Ulrich, R.B. & Quenemoen, C.K. (2013). A Companion to Roman Architecture. pp. 299-323. Blackwell Publishing: Oxford.
  13. Retrieved April 19, 2017 from Bathing culture
  14. Retrieved April 19, 2017 from Baths of Diocletian
  15. Retrieved April 19, 2017 from Bathing culture
  16. Retrieved April 19, 2017 from Rome
  17. Retrieved April 19, 2017 from Trajan
  18. Retrieved April 19, 2017 from Caracalla
  19. Retrieved April 19, 2017 from Baths Diocletian
  20. Retrieved April 19, 2017 from Comparison
  21. Retrieved April 19, 2017 from Persecution of Christians
  22. Retrieved April 19, 2017 from Diocletian's Persecution
  23. Retrieved April 19, 2017 from Roman baths
  24. Keightley (1841). From the accession of Augustus to the end of the Empire of the West. History of the Roman Empire
  25. Retrieved April 19, 2017 from Diocletian
  26. Retrieved April 19, 2017 from Maximian
  27. Retrieved April 19, 2017 from Diocletian and Maximian
  28. Yegul, Fikret (1992). Baths and Bathing in Classical Antiquity (First ed.). Cambridge, MA: MIT Press. ISBN 0-262-74018-4.
  29. Oates, W. J. (1934). The Population of Rome. Originally published in Classical Philology. Vol. 29, No. 2, pp 101-116.
  30. Beloch, K.J. (1886). Die Bevoelkerung der griechisch-roemischen Welt (Leipzig: Duncker & Humblot). pp.392-412.
  31. Retrieved April 19, 2017 from Map