4 Best Sights in The Algarve, Portugal

With high red walls that overshadow the little whitewashed houses below, this polygonal sandstone fortress was built between the 8th and 13th centuries and survived untouched until the Christian sieges. You can walk around inside the remaining walls or clamber about the crenellated battlements, taking in bird's-eye views of Silves and the surrounding hills. Its gardens are watched over by a statue of King Dom Sancho I, and its capacious water cistern is now a gallery space devoted to temporary exhibitions.

Once a Moorish stronghold, Loulé has preserved the ruins of the medieval castle, which was enlarged in 1268 after the site had been occupied and fortified since Neolithic times. There's an archaeology museum on-site to explore, too.

It was from the Manueline window of this palace that the young king Dom Sebastião is said to have addressed his troops before setting off on his crusade of 1578. The palace is long gone, though the section of wall with the famous window remains and can be seen in the northwest corner of the Praça do Infante. The crusade was one of Portugal's greatest-ever disasters, with the king and some 8,000 soldiers killed in Morocco at Alcácer-Quibir. (Dom Sebastião is further remembered by a much-maligned, modernistic statue that stands in Praça Gil Eanes.)

From the battlemented walls of the ruined 13th-century castle you can look down over Tavira's many church spires and across the river delta to the sea.