Fort San Andres is the last surviving fortification from the period of the Spanish Occupation of Trinidad, which came to an end in 1797 with the capture of the island by the British.
As early as 1733, a fortification called Fort San Andres was planned to replace a redoubt of fascines and earth, which was the only defense to Port of Spain.
The fort mounted five cannon and was "useful in maintaining good order among shipping anchored off-shore".
Late in the nineteenth century the shoreline was again filled to its present line, completely land-locking the Fort.
In 1995 the building was restored and converted to a museum of the City of Port of Spain.