The Castle of San Sebastián (Spanish: Castillo de San Sebastián) is a fortress located in Cádiz, Spain, at the end of La Caleta beach on a small island separated from the main city.

[citation needed] According to the classical tradition of the location of the fortress, there was a Temple of Kronos, a Titan of the Greek gods, the father of Zeus, Poseidon, Hades, Hestia, Demeter and Hera.

In 1457, a chapel on the island was raised by a Venetian boat crew recovering from the plague.

In 1811, the Maltese navy arrived with the famous POW/rebel Junta of Buenos Aires, Juan Bautista Azopardo.

He was housed in the fortress until 1815, when they suspected a leak and transferred him to the military prison in Ceuta.