Znojmo's labyrinth of underground corridors below the old town is one of the most extensive in Central Europe, snaking around for some 27km. Two types of guided tours are offered: the 'classic' tour is designed for families and features fairy-tale characters; the 'adrenaline' tour is more hardcore and involves actually climbing walls and crawling through tunnels.
Three types of adrenaline tours (blue, red and black) are available and ranked by difficulty (black is the hardest). Hard hats and proper outer gear are provided. Children under 15 are not permitted on the red and black tours.