Baths of Diocletian


A monumental complex unique in the world due to its size and exceptional state of preservation, the Baths of Diocletian represent one of the most emblematic sites of Rome 's millenary history (Via Enrico De Nicola, 79). Built in the fourth century A.D. they constitute the largest thermal establishment ever contructed in the Roman world. Trasformed by Michelangelo, who used the site to build the Basilica of St. Mary of the Angels and the Martyrs and the Charterhouse, the Baths have been home to the National Roman Museum since its founding in 1889.1


Baths of Diocletian

The Baths of Diocletian, the largest in the ancient Roman world, were built in just eight years, between 298 and 306, on a flat area between the Viminal and Quirinal hills. A large number of both private and public buildings were demolished to build the complex. The baths covered an area of more than 13 hectares, contained in a vast enclosure, with the main entrance on the north-easter side and, in the middle of the opposite side, a large exedra with steps corresponding to today's Piazza della Repubblica.


On both sides of the exedra there were two libraries. One of them was trasformed in 1598 into the Church of San Bernardo, while the other is still visible at the beginning of via del Viminale. The main halls of the frigidarium, tepidarium and calidurium were aligned along a central axis; all the other halls were placed symmetrically around this axis. The calidarium was built with specific architectural techniques that gave the impression of a more open space for the patron. Dressing rooms, also known as apodyteria, were located on either side of the calidarium. Along the sides of the calidarium were private rooms that are believed to have had multiple functions, including private baths, poetry readings, rhetoricians, etc. Other areas attached to the calidarium were a garden, lounging rooms, gymnasiums, and small halls and semicircular exedrae used as lecture and reading rooms. On the sides of the frigidarium were placed two large outdoor gymnasiums, the western one of which is partially visible in the archaeological area of Via Cernaia. Two octagonal halls were aligned with the calidarium.
One of these was used as a planetarium from 1928 until the 1980s.2


The baths take up 120,000 square metres of the district, wich is about the same size as the Baths of Caracalla. However, the capacity of the Baths of Diocletian was much greater than those of Caracalla. This could be because the entrance and the rooms allowed more spaces and functionality, considering that they were made larger than its predecessor in block size. The complex was restored at the beginning of the 5th century A.D. and maybe used for a few more decades. The Baths still retained much of their original decorations in the Renaissance, as shown by numerous artists’ drawings dating from the 15th and 16th centuries. After almost a thousand years, in 1561 Pope Pius IV decided to build a Basilica in the internal area of the Baths, consecrated to Our Lady of the Angels, with an attached Charterhouse, to commemorate the Christian martyrs who, according to the legend, died during the construction of the Baths. Michelangelo, commissioned to design the church, used both the frigidarium and the tepidarium areas without altering the original structures and planned the main cloister. During those years the small cloister adjacent to the church’s presbytery was built, and it occupies about a third of the natatio’s surface. Starting from 1575, with Pope Gregory Xlll, several halls of the Baths were converted into warehouses to store grain and oil.3


The Garden and the Krater-fountain

Since the foundation of the National Roman Museum in 1889, the Garden has been set aside for the display of numerous archaeological finds originating from Rome and its suburbs, datable between the late 1st century B.C. and the 3rd century A.D.
Inscribed funerary altars are arranged to the sides of the Garden’s entrance. Statues of togaed figures are displayed along the path leading to the museum, together with several architectural elements (columns, capitals and architraves) originating from various ancient buildings.4


The central fountain is dominated by the imposing volume of the colossal krater, which was already used as a fountain in ancient times, although its original placing is unknown. It is a rare artefact with only one other comparable example in Rome, the krater in front of the Basilica of Santa Cecilia in Trastevere. The fountain is surrounded by large inscribed funerary altars dedicated by relatives or heirs to senators, soldiers, foreign figures, a freedman of Caligula and the patron of a rich freedwoman. The path on the right is lined with funerary cippi and steles in travertine of various origins, including funerary steles dedicated to soldiers of different corps stationed in Rome and to the Imperial German Bodyguard.5


Present day

The last significant changes to the complex took place after the Italian capital’s transferral to Rome. Following the dissolution of the congregation of Carthusian monks, who definitively abandoned the Charterhouse in 1884, the area around the Baths was involved in large-scale town-planning interventions. As well as the construction of the Roma Termini railway station, the zone also became home to the Ministry of the Economy, the Grand Hotel, Palazzo Massimo, Piazza dell’Esedra, with the large buildings by G. Koch following the old exedra and destroying certain sections of it, and lastly Via Cernaia, which definitively separated the western gymnasium from the remains of the external enclosure, the latter still being visible along Via Parigi. In 1889, the complex of the Baths of Diocletian and the Charterhouse became the site of the National Roman Museum.6


The tepidarium and the frigidarium constitute the vestibule and central body of the Basilica of St. Mary of the Angels and the Martyrs, while the remains of the calidarium can be recognised on the facade.
Some of these have been incorporated into St. Mary of the Angels and the Martyrs, where the apse of the calidarium (on the facade), the tepidarium fend the large frigidarium can be recognised.7


The Church of San Bernardo is also built in one of the circular rooms of the other enclosure. On the other hand some the Aule delie Olearie, or Oil Warehouses, the largest public work carried out by Clement XIII in order to ensure an efficient supply of oil to Rome,are part of the museum; they stand to the right of the Basilica of St. Mary of the Angels and the Martyrs.8


  • Photos and main text by Chiara De Liso ti.supmacla|osiled.araihc#| and Martina Ciancio ti.supmacla|oicnaic.anitram#| (December 2015)

Related items


  • M.Barbera, Baths of Diocletian guide, Mondadori Electa, Verona 2014 pp. 79.


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