The Porta Nigra is the most important sight in Trier, and one of the most dominating. This huge entranceway to the city, which means Black Gate, was built by the Romans in the 2nd century. Originally another similar example would have stood at the southern entrance to town. It stands 36 metres long and 30 metres tall. It is the oldest surviving example of a defensive structure still standing in Germany. The two archways in the ground floor allow entrance to the courtyard beyond. The interior of the building was used as the church of St. Simeon from the 12th century to the early 19th century. The interior is open to visitors.
