A few miles inland, and not at all what you might expect to find in the beach-obsessed Algarve, stands one of Portugal’s finest castles. Its 10 towers crown the sleepy hilltop town of Silves, linked by an unbroken line of battlemented parapets that encloses an inner area of 4.6 square miles. Four of the towers include vaulted halls and Gothic doorways, added during medieval renovations.

Silves was the hub of Muslim Algarve, a vibrant, thriving cultural center that in the 11th century far outshone Lisbon and was compared to Cordoba for its mosques, palaces and medina. It fell first to Crusaders who drove out the Moors, then to earthquakes; but despite both, its castle remains the finest Moorish fortification in Portugal.

Archaeological digs continue to uncover remains of the 12th-century city and its Roman and Phoenician predecessors inside the castle walls, where you’ll also find peaceful gardens to stroll. The vaulted roof of a gigantic cistern, whose cavernous interior you can descend into via narrow stairs, dominates one end of the enclosure.

Walk along the top of the entire wall for views that extend over the tile rooftops of the town below and across orange and almond groves to the mountains.