Founded by the Roman emperor Augustus around 16 BC, Trier is now the oldest city in Germany. Consequently, it has more Roman architectural relics than anywhere else in Germany and these are the oldest Roman ruins outside of Rome. The ruins, combined with the Cathedral of St. Peter and the Church of Our Lady in Trier, earned a designation as a UNESCO World Heritage Site in 1986. The city's center is easily walkable with many of its main attractions within a 20-minute stroll of each other.
Outside of its Roman origins, Trier is also known as the birthplace of Karl Marx and you can visit the house in which he was born to learn more about his life and his Communist Manifesto.
Found on just about any river cruise itinerary that sails the Moselle River, Trier is also a thriving university city with lots of options for dining and shopping.