The Castell de la Trinitat crowns the Poncella point above the lighthouse of Roses. This military construction, which dates from 1544, was erected under the reign of Emperor Charles V.
It has the shape of a five-pointed star, with pronounced angular corners for defence against enemy projectiles. It is built on a very grand scale, with walls two metres thick. It had three terraces for batteries of cannons, howitzers and mortars, set at different heights, to defend the port and the coast. It had a garrison of up to two hundred men. Though now in a very ruined state, the whole remains as an extraordinary example of a coastal artillery fortress.