The Castle of St John the Baptist, also called the Black Castle, is a circular fort in Santa Cruz de Tenerife in the Canary Islands. It is located in the heart of the city, near the Parque Marítimo César Manrique and behind the Auditorio de Tenerife. Construction began in 1641 and was completed in 1644. The structure was later rebuilt in 1765 with the addition of a cylindrical tower facing the sea. It served as a military fort until 1924 and was converted to a military museum in 1948. A re-enactment of the Battle of Santa Cruz de Tenerife takes place annually at the castle, commemorating the unsuccessful attempt by the British admiral Horatio Nelson to invade the city and archipelago on 25 July 1797.Photograph credit: Thomas Wolf