St Lambert's Church (Lambertikirche) dates mainly from the late 14th and early 15th centuries and is notable for its unusual octagonal tower, a Westphalian Gothic peculiarity. The church was the centre of the 1534–35 Anabaptist uprising — the radical Protestant sect took it over, removed the altars, melted down the artwork, and installed their own regime in the city. After the city was retaken by the prince-bishop's forces, the Anabaptist leaders were tortured and executed in the market square outside.
The three iron cages hanging from the tower are the most arresting detail — visible from the street and still striking more than 480 years after they were put up. The church interior has good late-Gothic vaulting and is free to enter. The Roggenmarkt immediately north of the church is a pleasant square with cafés and a small weekly market.