Ravelin Peter protected the entrance to Petersberg Fortress from 1708. The main moat bridge was built in wood from 1665 and secured with a drawbridge. In 1864, it was rebuilt as a stone arch bridge with seven bays and another drawbridge. This was no longer needed when the fortress status was abolished in 1874 and another stone arch was built in its place. After 1920, the moat was partially filled in and the arches walled up. The ravelin and moat were restored in the 1990s.