Porta Nigra (Black Gate), Trier (must see)

Black Gate is an ancient Roman city gate and the largest Roman gate north of the Alps. It is part of Trier's UNESCO World Heritage Site.

The Black Gate name originated in the Middle Ages and refers to the darkened stone color. The Roman gate was built after 170 AD and used as a town entrance for centuries. The gate was built with 7200 massive sandstone blocks that weigh as much as six tons and are held in place by iron clamps. The construction of the gate was never completed for unknown reasons. Black Gate guarded Trier's northern entrance and was one of four city gates.

During the Middle Ages, the other three gates fell into disuse, and their stones were used for other building projects. However, the Black Gate had important historical value as revered Greek monk Simeon's home. Simeon was a religious hermit who sought sanctuary in the Black Gate during the 11h century. The Black Gate was then turned into two churches. Monks used the upper church, and the lower church was available to the public.

Napoleon Bonaparte dissolved the church in 1802. Bonaparte wanted to tear down the structure, but residents convinced him to save it and restore it to its Roman origins.

Visitors can see the remains of Roman columns leading up to the gate. Black Gate is open to visitors, and during the summer, an actor portraying a Roman army officer leads tours. Visitors can climb to the gate's top for commanding views of Trier.