St. Julian's is a British international private school located in the parish of Carcavelos e Parede,[1] in Cascais, close to Lisbon, Portugal.

The school takes its name from São Julião da Barra Fortress, overlooking nearby Carcavelos beach, originally erected in the mid-16th century to keep the British, among other raiders, out of the Tagus estuary.

In the early 20th century, Carcavelos in Portugal had an Eastern Telegraph Company (ETC) station that used underwater wires to send communications internationally.

In 1932, a Mrs Bucknall, who had connections with the Parents’ National Education Union (PNEU), began working towards creating an English-speaking school in the area.

Mrs Franklin CBE, a PNEU committee member, came to Portugal on a short visit that year, and was influential on the pedagogy of the new school.