Underground water drainage system in Slavonice, Underground drainage system in Slavonice, Czech Republic.

The Slavonice underground is a system of passages beneath Míru Square, dug by hand into the rhyolite rock, probably by miners from the Jihlava region. The drainage corridors are very small, averaging 150 cm in height and 60 cm in width, and connect cellars carved in the 13th and 14th centuries. About 1.5 km of the cleared section is open to visitors.

The system was built during medieval times when the town needed protection from water damage as it expanded. Builders created these underground passages to solve the practical challenge of managing water in a low-lying area.

The drainage system is woven into how locals understand their town's relationship with water and survival. People pass down stories about the tunnels and how earlier generations managed the constant challenge of moisture and flooding.

Access to the system is limited and visitors should check ahead about which sections are open since not all areas are always accessible. Tours work best on dry days, as rain can raise water levels in certain passages making exploration difficult.

The drainage tunnels are tiny: an average profile of 150 cm in height and only 60 cm in width, cut by hand into the rhyolite bedrock, probably by miners from the Jihlava region. They were never meant for people, only for groundwater flowing toward the town moat.