Petersberg Citadel, the only extensively preserved town baroque fortress in central Europe, was built on the site of a former Benedictine monastery.
It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
Tram no. 3, 4 or 6 to Domplatz
By car: Domplatz multi-storey car park