Silves Cathedral stands just below the castle, a Gothic building that has been damaged by earthquake and rebuilt multiple times but retains a certain plain dignity. The original structure dates from the late thirteenth century following the final Christian reconquest of the city; the current building is largely Gothic with later additions. The façade is unassuming from the outside, but the interior is cool and high, with ribbed vaulting and a handful of notable tombs.
The exterior reveals the building's history well: you can see clearly where different building campaigns left their marks on the stone. The portal decoration is Gothic, the stone itself the distinctive reddish sandstone of the Algarve. The nearby bishop's palace (now municipal offices) and the old seminary are also worth a glance as you pass.
Entry is inexpensive. The cathedral can be combined with the adjacent castle in a single visit, and together they give Silves the best concentration of historic monuments in the Algarve interior.