Kaiserthermen (Imperial Roman Baths), Trier (must see)

The Imperial Roman Baths were constructed during Constantine I's reign in the fourth century. Trier's baths are the largest Roman baths outside of Rome. The original bathing structures were over 200 meters long (656 feet) and 100 meters wide (328 feet).

Constantine started building the baths as part of a city-wide building project. Trier was one of the Empire's most important cities and considered a "Second Rome." Roman Trier was home to between 75,000 and 100,000 people.

Bathing was an important part of Roman culture, and the baths were open to the public. The hot water pools reached 40 Celsius (104 Fahrenheit), and the complex had an underground tunnel system for staff. During the Middle Ages, the baths were turned into a castle. The baths have also been used as a city wall and a monastery.

Today's visitors can tour the baths and the underground passageways. The Imperial Roman Baths are part of Trier's UNESCO World Heritage Site.