Porta Nigra

Trier: The Porta Nigra, viewed from outside

The Porta Nigra (black gate) in Trier is a large Roman gatehouse with two four-storied towers, projecting as near semi-circles on the outer side. The structure is largely of grey sandstone, and was built between 180 and 200. In the Middle Ages, the building was used as a church, one of the towers being adapted to contain an apse.