The Miner’s Bastion began as a semi-circular bastion in the castle walls. In the second half of the 15th century, a polygonal structure was built above it as the presbytery for a chapel dedicated to the Birth of the Virgin Mary. This was built around 1450 for a townsman called Langsfelder. It had a short rectangular nave whose foundations were uncovered during archaeological research. The chapel was probably demolished as early as the 16th century, when the bastion was restored. The name Miners’ Bastion suggests that the bastion was guarded by miners in times of danger.