This fort at the eastern end of Puerta de Tierra was completed in 1788 to guard the entrance to Laguna del Condado. It was barely up and running in 1797 when the British came marching through to San Juan and a short-lived occupation. Restored in 1983, today San Gerónimo is managed – and hemmed in – by the Caribe Hilton. The fort has fallen into such disrepair, though, that visitors are no longer permitted to enter the site.

Its walls and turrets can still be seen from the road leading up to it as well as from Condado, across the inlet. A silent reminder of San Juan's past.