The Fort of Our Lady of the Conception, also known as the Portuguese Castle, is a red stone fortress on Hormuz Island, Iran. It is one of the last surviving monuments of Portuguese colonial rule in the Persian Gulf. Constructed on reddish stone on a rocky promontory at the far north of the island, the castle was originally cut off from the rest of the island by a moat, traces of which still remain. Although most of the roof caved in long ago, much of the lower part of the very substantial outer walls is intact, with the remains lying on different levels of the site.