I will look at the history, architecture, art, and many other aspects of this ancient bathing complex. And though some parts of the Baths of Diocletian have vanished, nevertheless, the vast ruins, thick walls, and spaces that exist today are still impressive and monumental.

A leisurely walk from the Colosseum will get you to the Baths of Diocletian quickly, as shown in the map guide below followed by 2026 ticket information. The suggested walking path below is approximately 1 mile (1.6 km) and takes about 20 to 30 minutes. The Rome Termini Train Station is just east of the Baths of Diocletian, as is the Rome Metro Termini Subway Station which are both very close to the baths.

INTRODUCTION

In 306 AD, with the completion of the Baths of Diocletian, Roman baths reached their peak not only in size but also in luxury. Even today, the current basilica inside the former ancient Frigidarium is still one of the most exhilarating interior spaces in the entire city of Rome. To the Romans, these baths were known by the name: "Thermae Diocletiani."

This colossal building complex was a larger version of the vast Baths of Caracalla that opened 90 years earlier in 216 AD. Huge baths like these are why, long after the Roman empire had fallen, people once thought that giants had built Rome because of the size and scale of the ruins they left behind.

Built of concrete and millions of bricks, the Baths of Diocletian was decorated lavishly with marble walls and floors, hundreds of columns, frescoes, mosaics, numerous statues, and large upper windows that filled the interior with sunlight.

Furthermore, the size of these baths, including the surrounding outside gardens, walls, and other structures, measured 13 hectares (32 acres). The actual main baths building itself was an incredible 4.5 hectares (11 acres) in size. One can only marvel at the labour, resources, expertise, artistry, and planning required to build such a massive complex in only eight years (298 - 306 AD).

Baths of Diocletian Main Hall in 4th century
From floor to ceiling was seven storeys in height
From a drawing by Edmond Jean-Baptiste Paulin, 1880, Modified

In ancient times, undoubtedly the Baths of Diocletian complex was an outstanding sight with its vast spaces, marble-covered walls, beautiful mosaics, statues, and frescoes. The image above aptly shows how massive this bathhouse was, and this is just a partial view of the Main Hall showing parts of the Frigidarium and Tepidarium areas.

Notice how the high, vaulted ceilings cover a considerable area of marble floorspace below. This high ceiling's vaults are supported by eight huge columns made of red granite from Egypt, and they are still there supporting the original ceiling today. These columns are 17 metres high (56 feet) and 1.6 metres wide (5 feet).

The incredible amount of detail and decoration you see displayed throughout the drawing above was typical of Roman design, which loved splendour and luxury. There is a pool on the left and right sides with an even larger pool in the distance. There are also large "tubs" at various locations on the floor. And, like many large Roman buildings, the brick superstructure was covered with marble on the inside and white stucco on the outside.

Baths of Diocletian interior Main Hall in the 21st Century

In the image above, we see the same Main Hall of the Baths of Diocletian as it looks in the 21st century (2008). The view is of the same large, arched passageway on the right side of the fourth-century drawing above the photo. Amazingly, those reddish-granite columns and capitals (as well as the ceiling) in the drawing have miraculously survived a 1,700-year journey through sackings, wars, pillaging, earthquakes, and neglect.

If you think that the photo above looks like the inside of a church, you are correct. In the 16th century, this church was designed by the great artist and architect Michelangelo. He built this church (basilica) while using as many of the original materials as possible, within the ancient Frigidarium and Tepidarium, of the Baths of Diocletian.

The alternating diagrams below show the outlines of the Baths of Diocletian and the Baths of Caracalla, so you can compare them. You will see that the main building of the Baths of Diocletian was larger. However, you will also notice many similarities such as:

Another shared characteristic is that both these baths were built mainly of bricks and concrete covered with a marble veneer on the inside and white stucco on the outside.

In the diagrams below, please note that, although the Baths of Diocletian main building is 20% larger, the Baths of Caracalla complex (building and surrounding gardens, walls, etc.) occupied a more extensive area - 25 hectares (62 acres) versus the Baths of Diocletian's smaller 13 hectares (32 acres).

Notice how the Baths of Caracalla has large and circular exedras on the lower left and right sides of its outside wall. In comparison, the Baths of Diocletian, in addition to its huge bottom theatre exedra, also has numerous circular and rectangular exedras all along the other three surrounding walls.

The semi-circular exedras are said to have a "hemicycle" shape, meaning semi-circular. The arrangement of the water pools is precisely the same. In addition, both baths have two Palestrae (exercise area) areas, one on either side of the Frigidarium water pool.