Trier Gate, Medieval city gate in Bastogne, Belgium

The Trier Gate is a square tower about 8 m wide and 17 m high, built of local Ardennes schistose sandstone with a two-level slate roof. A tunnel runs through it from north-west to south-east, once closed by two doors: the outer south-east door has a pointed arch topped by a small niche with a statue, the inner north-west door a round arch. Three machicolations crown the upper part, and short wall stubs on the north-east and south-west faces mark the line of the former ramparts.

In 1332 Jean the Blind, Count of Luxembourg and La Roche, ordered walls with about a dozen defence towers and two gates built around Bastogne; they were erected between 1341 and 1360. In 1688 Louis XIV of France had the walls demolished, and the Trier Gate, the only element still standing, became a prison. Bombardment during the siege of Bastogne in December 1944 and January 1945 heavily damaged it, and it was rebuilt after the war.

The gate is also called the lower gate, porte basse, because it stood in the lower part of Bastogne, near the Saint-Pierre church. Its name refers to the road toward Trier. The Cercle d'Histoire de la ville organizes temporary exhibitions there, and groups can visit by appointment.

The gate stands at the crossroads of rue Piconrue, rue des Quatre-Bras and rue Porte de Trèves, northeast of Bastogne's historic centre, behind Saint-Pierre church. Group visits, including school groups, are by appointment only; temporary exhibitions are organised by the Cercle d'Histoire. The building has no lift, and the upper levels are reached by stairs.

The gate's survival is partly accidental: in 1688 Louis XIV ordered the walls demolished, yet this tower was kept and turned into a prison. It is now the only standing element of Bastogne's dozen defensive towers and two gates, and is listed as exceptional Walloon heritage.