The imposing castle dominates the image of Blankenheim. Finds indicate that a Roman fort previously stood here. Gerhard I built the castle in 1115 above the source of the Ahr. Today the castle complex serves as a youth hostel and can be visited on request. Blankenheim Castle is located directly on the hiking trails Burgen-Route and Eifelsteig stage 6.
Until far into the 19th century millstone were carved out in the caves. But the caves also were used as natural "refrigerators". In the winter time they were equipped with ice and snow so that cooling conditions kept the cold far into the summer.