Rudolfova štola, Underground water tunnel in Holešovice, Czech Republic

Rudolfova štola is an underground water tunnel beneath Prague spanning about 1,100 meters with a width of less than 1 meter. The passage stands 2 to 3 meters high and connects two locations through the rock beneath the city.

Rudolf II commissioned the tunnel in 1583 to feed a pond in the Royal Game Preserve, using the fall between the Vltava at the Old Town and at Stromovka. Lazar Ercker and Jiří Oeder sank five shafts from 1584, and the tunnel itself was driven from 1589; the miners broke through on 17 July 1593.

The tunnel carries the name of Emperor Rudolf II, who ordered it in 1583 to fill a pond in the Royal Game Preserve. Its Stromovka portal bears a stone crown, the year 1593 and the initial R. The tunnel is closed to the public, but the portal and the shafts' covers can be seen from outside.

The tunnel is closed to the public; only the intake house on the left bank of the Vltava below Letenské sady, between Čechův and Štefánikův bridges, and the brick portal in Stromovka Park can be seen from outside. The Stromovka portal bears a crown, the year 1593 and the initial R.

The project required five deep shafts about 33 to 39 meters down just to dig the tunnel from above. These shafts were the only way to handle the heavy work at such depth beneath the city.