The Fort of São Sebastião de Caparica (Portuguese: Forte de São Sebastião de Caparica) also known as the Tower of São Sebastião (Portuguese: Torre de São Sebastião) or Fortress of the Old Tower (Portuguese: Fortaleza de Torre Velha) is a medieval fortification located in Monte da Caparica, civil parish of Caparica, in the municipality of Almada, in the Portuguese central region of Península de Setúbal.