Black Tower, Fortified tower at Prague Castle, Czech Republic

The Black Tower is a fortified stone tower in the eastern part of Prague Castle, built with thick walls and Romanesque details. It originally served as the eastern gate to the castle and today houses an archaeological collection related to the fortress.

The tower was built in 1135 as the eastern gate of the castle's fortifications. Before a fire in 1541 darkened its walls and gave it its current name, it was called the Golden Tower under Charles IV, whose roof was covered with gilded lead plates.

The tower's name comes from the soot of the 1541 fire, which blackened its walls so much that it became known as the Black Tower. In 1547, over 600 people were arrested during the revolt of the Czech estates against Ferdinand I; the Old Town chancellor Sixt of Ottersdorf was thrown into a foul-smelling cellar here before being moved to milder confinement.

The tower stands at the eastern entrance to Prague Castle, where the Old Castle Stairs (Staré zámecké schody) lead up to it. It is not open to the public, as it houses a depository of archaeological finds from the castle; the gate beside it now forms the eastern access route.

The tower's foundations are older than the tower itself: they come from an 11th-century structure. The pyramidal roof was later covered with gilded lead plates under Charles IV to signal to visitors that they were approaching the seat of a powerful ruler.