Trier Imperial Baths

The Kaiserthermen in Trier are the ruins of a bath palace that was never used as one. Work began shortly before 300 AD, when Constantius Chlorus and then his son Constantine made Trier, Roman Augusta Treverorum, one of the capitals of the western empire. The complex was planned on a scale meant to match the baths of Rome itself, with a great exercise court and a symmetrical sequence of cold, warm and hot halls. Around 316, when Constantine was drawn into his war with Licinius and later moved his court east, building stopped with the shell standing and the plumbing never finished.

What survives is the eastern end, the caldarium or hot-bath hall, with walls still up to 19 metres high and three great apses. The masonry is the thing to look at: bands of red brick laid between courses of limestone blocks, a Roman technique that gave the concrete core strength and that the builders fully expected to hide under plaster and paint. The whole complex covered about 250 by 145 metres. Below ground runs a network of service tunnels meant for the staff who would have fed the furnaces out of sight of the bathers; they were never put into use, and walking through them is the most atmospheric part of a visit.

The building had several afterlives. Later in the fourth century, under Emperor Gratian, the unfinished shell was turned into barracks for the mounted imperial guard, and the cold hall was pulled down. In the Middle Ages the caldarium became a fortified corner of the city wall, with a gate through it, and a Trier family took its name from living in the ruin. Clearance of the hot hall began only in 1816, and systematic excavations before the First World War settled the long argument over whether this had been a palace, a church or a bath; the underground passages were opened to the public in 1920.

Today the site is an archaeological park and part of Trier's World Heritage Site of Roman monuments, the cathedral and the Church of Our Lady, inscribed in 1986. Entry is through a long, low modern building by the architect Oswald Mathias Ungers, with a small exhibition and a viewing tower over the ruins, and since the late 1990s the caldarium has regularly been fitted out as a stage for open-air events. Trier's other Roman baths, the Barbara Baths, were in fact older and larger, but the Kaiserthermen are by far the better-preserved.

Getting there

The baths are in central Trier, about 15 minutes' walk from the Porta Nigra; city buses 3 and 4 stop at "Kaiserthermen". The closest airport is Luxembourg (LUX), about 34 km away; within Germany, Frankfurt-Hahn (HHN) is about 50 km by straight line.