In the Old Town are 216 buildings under monumental protection. On the west side of the Old Town are found the monastery ruins. They are Europe’s biggest ecclesiastical ruin, and are now used as a venue for the "Bad Hersfelder Festspiele". In the monastery zone stands the Katharinenturm (tower), in which hangs the "Lullusglocke", Germany’s oldest dated bell (cast in 1038 AD). Furthermore, a wing of the cloister has been preserved (today a museum; chapter house preserved) and likewise great parts of the remnants of the town wall (South Gate, "Halbschalenturm" or "Half-Shell Tower"). The two "Nordschulteiche" (ponds) in the Leonhard Müller Complex are leftovers of the town moat. In this park is also found Saint Vitalis's Cross (the original can be seen in the museum). It stands on the spot where the townsmen fought off the attack by the "Sternerbund" in 1378. Further remnants of the town fortifications stand in the Lower Town (east side of the Old Town), among them the "Klausturm" (a watchtower and prison) and the somewhat smaller "Pulverturm" ("Powder Tower")