The project was originally commissioned by Maximian upon his return to Rome in the autumn of 298 and was continued after his and Diocletian's abdication under Constantius, father of Constantine.

The site houses the Basilica of Santa Maria degli Angeli e dei Martiri, built within the ruins in the 16th century, the Church of San Bernardo alle Terme, and part of the National Roman Museum.

The baths occupy the high ground on the northeast summit of the Viminal, the smallest of the Seven hills of Rome, just inside the Agger of the Servian Wall (near what are today the Piazza della Repubblica and Termini rail station).

The water supply was provided by the Aqua Marcia,[3] an aqueduct that had long served the city of Rome since the early 2nd century.

Evidence of this can be found in bricks from the main area of the baths, which distinctly show stamps of the Diocletianic period.

This evidence shows the effect of the massive project on the brick industry in that all work by them was redirected and under the control of the emperor.

[2] In the 1560s, Pope Pius IV ordered the building of a basilica in some of the remains, to commemorate Christian martyrs who according to legend died during the baths' construction, Santa Maria degli Angeli e dei Martiri.

A small cloister next to the presbytery of the church was built, occupying part of the area where the baths' natatio had been located.

After 1575, starting under Pope Gregory XIII, several remaining halls of the baths were converted into grain and oil stores for the city of Rome.

Roma Termini station was built, the Ministry of the Economy moved to the area, and the Grand Hotel and Palazzo Massimo were constructed.

Ancient marbles and alabasters, bronzes, costly metals and relics beautified with precious stones, medieval parchments and church ornaments, oriental ivories, velvets and silks hung on all sides, in alluring contrast to the latter-day furniture and the twentieth-century grand piano, proclaiming the broad sympathies and the catholic tastes of this citizen of the world.

[9]: 230 Ezekiel's studio was regarded as "one of the Show Places of the Eternal City, magnificent in proportions and stored with fine artworks.

"[10] He held an open house there every Friday afternoon,[11]: 233  in addition to hosting musicales,[8]: 42  where could be heard "the finest music by the greatest talent".

[12]: 233  Visitors to his studio included: After 30 years, the government "demand[ed] the possession of this part of the ruins as an adjunct to the National Roman Museum.

"[2] Although only fragments of the inscription are extant today, a complete transcription was made by an 8th- or 9th-century pilgrim and was preserved at Einsiedeln Abbey in Switzerland.

The frigidarium, or cella frigidaria consisted of a pool and a host of smaller baths connected to the main room.

[2] This technique was quite common within the structures built during the Imperial style of Roman architecture, e.g., the baths of Constantine, the Basilica Nova, and parts of the Sessorian bridge.

[1] The Smithsonian's National Museum of Natural History building in Washington, D.C., was partially based on design elements from these baths, including its Diocletian windows.

[6]: 7 The museum is located in what is known as "Michelangelo's Cloister" and other buildings that were part of the Carthusian monastery as well as several halls south of the eastern palestra.

The church of San Bernardo alle Terme uses one of only two circular buildings in the rectangular enclosure of the baths, flanking its southwestern wall.