The Silesian Ostrava Castle is the city's most historic cultural monument. It was built in the second half of the 13th century, close to the confluence of the Lučina and Ostravice rivers, where a fortified Slavonic settlement had once stood. In 1872, the castle burnt down, but was later re-built. The main cause of its destruction was coal-mining, with seams worked directly beneath the castle. The whole structure sank 16 m into the ground! The castle has been reconstructed and visitors now can view in its interior several permanent exhibitions telling the history of the building and the city of Ostrava, an exhibition of torture instruments, the castle’s vaulted cellars with witches, fresh-water fish aquaria and the castle gallery.