Significance. La Fortaleza (The Fortress) was the first true fortification in San Juan, established in 152l. The Spanish built it between 1533 and 1540 for protection against raids by Carib Indians and by English and French freebooters.

It is the Portuguese word for Flemish, and it was given to the nearby beach (Praia do Flamengo, Beach of the Flemish) because it was the place where the Dutch sailor Olivier van Noort tried to invade the city in 1599.