The best known of the Saxon country's fortress churches has a circular surrounding wall, within which 270 rooms, along with a network of galleries and wooden ladders, enabled peasants to store harvests and provisions in the event the city was attacked. From a first courtyard, closed off by a barbican, a vaulted, half-moon gallery gives access to the central courtyard in the centre of which the church stands (mid-13C) contains a superb painted retable.