Germany's oldest city and Rome's northern capital — where the Porta Nigra (170 CE) is the best-preserved Roman city gate north of the Alps, four UNESCO-listed Roman monuments stand within walking distance, and the birthplace of Karl Marx sits beside a 4th-century imperial throne room that is still used as a Protestant church
Trier (115,000) on the Moselle River is Germany's oldest city — founded as Augusta Treverorum around 15 BCE by the Emperor Augustus. In the 3rd–4th centuries Trier served as the administrative capital of the western Roman Empire, rivalling Rome and Constantinople in grandeur; Emperor Constantine I held his court here for thirteen years. Four UNESCO World Heritage monuments survive from this era: the Porta Nigra (170 CE, best Roman city gate north of the Alps), the Imperial Baths (Kaiserthermen, begun c. 293 CE), the Amphitheatre (1st–2nd century CE), and the Cathedral of St. Peter (begun unde…
Augusta Treverorum was established as a Roman provincial capital around 15 BCE and grew to a city of 70,000–80,000 inhabitants at its peak under Constantine I (western capital 306–316 CE). The Aula Palatina (Basilica of Constantine, completed c. 310 CE) — a throne room 67m long and 27m high with underfloor heating — still stands and is now used as the Protestant Evangelical Church of Trier. The Gold Hoard of Trier, discovered by construction workers in 1993 and now in the Rheinisches Landesmuseum, contains 2,650 Roman gold coins — the largest Roman gold coin hoard ever found — hidden in a cla…