Porta Nigra
The Black Gate is the best-preserved Roman city gate north of the Alps. Large sandstone blocks were laid without mortar, held together with iron clamps. The gate survived because it became a church in the 11th century, and today it stands free again.
Augusta Treverorum, today’s Trier, was one of the most important Roman cities north of the Alps and later a seat of emperors. The city was given a wall with several gates, and the Porta Nigra was built around AD 170 as the north gate. It is built of grey local sandstone. The blocks weigh up to six tonnes and were laid without mortar; they were held together with iron clamps fixed with lead. The building work was never fully finished, and some surfaces were never fully dressed. The name Porta Nigra, the black gate, is medieval and refers to the dark colour of the stone.
The gate has two towers projecting towards the field and two gateways between them. Behind them lay a courtyard that could be closed with further gates, so that enemies who got in were trapped. The façades are divided by rows of arches with half-columns on several storeys, a typically Roman way of giving dignity to a fortification.
In the 11th century the Greek monk Simeon settled in the gate as a hermit. After his death the archbishop had the gate converted into a two-storey church, and a Romanesque choir was added. In 1804 Napoleon had most of the church removed and the Roman gate freed. The apse was allowed to remain. In 1986 the Porta Nigra became part of the World Heritage Site of Trier’s Roman monuments, cathedral and Church of Our Lady. The gate shows how ancient buildings were often saved by being given a new use.