Porta Nigra is a large Roman city gate located in Trier, Germany. It is the best-preserved Roman city gate north of the Alps and has been designated a UNESCO World Heritage Site since 1986. The gate was built in the 2nd century AD and was originally part of a much larger Roman city wall.

The name Porta Nigra (meaning "Black Gate" in Latin) is derived from the dark color of the stone used in its construction. The gate is made of large blocks of sandstone that were quarried from nearby hills. The gate consists of four levels and is approximately 30 meters high.

Over the centuries, the gate has been used for a variety of purposes, including as a church, a hermitage, and even as a residence for a bishop. During the Middle Ages, the gate was part of a larger complex of buildings, including a monastery and a church, that were built within its walls.

Today, the Porta Nigra is one of Trier's most popular tourist attractions and is open to visitors year-round. Visitors can climb to the top of the gate and enjoy views of the surrounding area, or explore the gate's interior, which contains a small museum about its history and construction.