One of the bastion’s two casemates was part of the town’s first bear pit and served as night-quarters for the bears for many years. The casemate was probably buried during the construction of the new bear pit in 1970 and may still be underground. The hills downstream (for example, the hill where the bronze statue of the bear is located) are remnants of the Lunettes of Aylva, other fortifications that used to be located here in front of the city wall. The stairs that lead over these hills have bluestone cordons that come from a demolished fortress. There are similar blocks on top of the walls of Wilhelmina.
The Wilhelmina Bastion was built in 1768-1769. A bastion is a pentagonal fortification with two sides facing the enemy, the faces; two walls facing to the side, the flanks; and one side facing the city, the gorge. Like all exterior structures, the fortress is predominantly made of earth and has masonry walls on the outside. The walls were fifteen feet high and were surrounded by a moat. A brick casemate and a gunpowder cellar were located in the bastion.
The bastion was named after Princess Wilhelmina, the Prussian wife of Stadholder William V.
The left face with the name stone Wilhelmina 1769 has been preserved. The upper section of the bastion’s wall was probably demolished after the ‘fortified town’ status was removed. The lower section of the walls was buried, as in many places in Maastricht. Also, the casemate and gunpowder cellar are probably still there, underground.