Old water tower in Plzeň, Water tower at Prazska Street, Plzeň, Czech Republic.

The old water tower in Plzeň, also called the Black Tower, is a five-storey building with a square plan and a pyramidal roof, attached to a single-storey water house. It stands on Pražská Street at the entrance to the historic centre. A late Gothic portal from a demolished house in Prešovská Street was set into its facade in 1922.

The first written record of Plzeň's water supply dates to 1532, when master pipe-layer Jindřich of Prague worked on it; the tower itself was built about ten years later and fed the fountains on the main square. After the Prague Gate was demolished in 1822, the tower was rebuilt in late Neoclassical style. A major reconstruction in 1845–1849 added one storey and replaced the old engine room with the adjoining water house, whose basement held a water wheel drawing from the Mlýnská strouha. Operations ceased in 1889 when the new municipal waterworks opened above the Úhlava–Radbuza confluence.

The tower's upper floors now hold a gallery of modern art, a museum devoted to the Škoda family of Plzeň, a jewellery shop and a tattoo salon. The Škoda plaque on the facade recalls Josef Škoda, after whom the late-Gothic portal beneath it was placed there in 1922.

The tower stands on Pražská Street at the entrance to the historic core, with the one-storey water house attached directly to it. Its underground section is part of the guided tour of the Plzeň underground; the upper floors hold a modern art gallery, a museum on the Škoda family, a jewellery shop and a tattoo salon.

The late-Gothic portal was taken from a demolished house in Prešovská Street and set into the tower's facade in 1922, beneath the Josef Škoda memorial plaque. In the same year the tower was stripped of its plaster up to the top floor.