The Jihlava underground with a total length of 25 kilometers is the second largest in the Czech Republic. Corridors were carved into the rock in several levels during the 14th to 16th centuries, up to a depth of 14 meters. They served as cellars for storing food and goods, during the Second World War partly also as an anti-aircraft shelter. The greatest rarity and mystery of the underground is the corridor, the walls of which glow greenish when illuminated. Collectors and a civil defense shelter from the last century are part of the underground.