UNESCO World Heritage Site in Rhineland-Palatinate, Germany
The Trier Imperial Baths (German: Kaiserthermen) are a large Roman bath complex in Trier, Germany. The complex was constructed in the early 4th century AD, during the reign of Constantine I. During that time, Trier was a major imperial hub, being a primary residence for Constantine's son Crispus. The baths were built around hot water pools reaching 40°C.[1] Underneath the complex was a network of underground passageways used by the staff which can still be seen today, along with the remains of the sewer system.[1] However, the baths were never completed and were made into a castle in the Middle Ages.[2]