The ruins of Toruń Castle stand on the south side of the old town, close to the Vistula. Built by the Teutonic Knights in the 13th century, it was one of the order's main strongholds in the region. After Toruń defected to the Polish Crown in 1454, the city's inhabitants tore the castle down — a deliberate act of rejection rather than war damage — and the ruins have remained in this state ever since.
The site is open to visitors and contains a small exhibition in the preserved cellars. What remains is atmospheric rather than grand: low walls, vaulted underground rooms, and a single tower stump above the river. The position above the Vistula is worth the visit on its own. Evening concerts and events are sometimes held in the open-air ruins during summer.