The Castillo de San Cristóbal (Castle of San Cristóbal) in Santa Cruz de Tenerife (Canary Islands, Spain) was the first fortification of significance on the island of Tenerife and the main defensive building on Santa Cruz Bay.
There remain only a few walls of the original building on display in an underground tunnel in the Plaza de España in the city. The central Castle Street is named after this fort.
Under the administration of Gov. Álvarez de Fonseca, construction began in 1575 but it was the January 20, 1577 when it entered service. After the construction of the Plaza de España, the castle was buried under it for centuries.
On June 28, 2006, during the refurbishment of the Plaza of Spain, some remains were later found to belong to the castle. At that time were taken precautionary and protective measures in order to ensure the preservation of the find. Today, the castle is a museum which houses the famous "Cañón Tigre" (Tiger Canyon), which according to tradition was used by Admiral Horatio Nelson in 1797.