The Pfaffenteich — "Priests' Pond" — is a rectangular artificial lake dug in the twelfth century to power a mill, now sitting at the heart of the city. It is ringed by nineteenth-century villas, the Arsenal building, and green promenades that make a fine morning walk. The Arsenal on the northern bank, a classicist brick building from the 1840s, is now used as an events venue. Swans occupy the lake year-round and have been a symbol of the city for centuries.
The Pfaffenteich is a five-minute walk from the Hauptbahnhof and most visitors pass it without giving it much attention, which is their loss. The lakeside café terraces on the southern bank are among the pleasanter spots in town for a coffee.