The only gate out of former six that still remained standing. It is named after Saint John the Baptist and together with the fortification it used to protect the city against the invaders.
More info at sanjuanpuertorico.com http://sanjuanpuertorico.com/la-puerta-de-san-juan-san-juan-gate/
Address Cll Caleta De San Juan, San Juan, 00901, Puerto Rico
Coordinates 18°27'54.626" N -66°7'10.071" E