Černá věž, Castle ruin in Nejdek, Czech Republic.

Černá věž is a castle ruin perched on a hill in the Nejdek region, consisting of stone walls that form the remnants of an old fortification. The structure rises prominently across the landscape and offers views of the surrounding terrain.

The castle was first documented in 1240 through Fridrich of Nejdek, and its square tower was built in late Romanesque style. In 1341 Petr Plik received it as a fief from King John of Luxembourg. The Schlick family acquired it in 1446 and held it until 1602, when Štěpán Šlik sold it to Bedřich Colonna of Fels. By then it was already unoccupied, and in 1623 Heřman Černín of Chudenice bought a site reduced to the Black Tower, used as the bell tower of St Martin's Church.

The tower became the bell tower of St. Martin's Church; a bell cast in 1656 on the order of Humprecht Johann Czernin hung here, and the smaller Barbara bell, cast in 1578 for Countess Barbara Schlick in memory of her husband, was melted down in 1917. A tower watchman lived in a room in the tower until 1790.

The tower stands on a rock spur above the Rolava river in the centre of Nejdek, reachable on foot from the town streets. The keep is the only surviving part of the castle; the palace traces and the moat lines lie on the rock around it. The tower interior is not described as open to visitors, so the structure is best seen from outside.

The walls display different stone-laying techniques from various construction phases of the fortress. These varying methods allow visitors to observe different periods of building and maintenance simply by examining the stonework closely.