Praia do Castelo is a beach[1] close to the village resort of Sesmarias which is within the Municipality of Albufeira, in the Algarve, Portugal.

The main beach is small and made up of gold sand and is 200.00 metres (656.17 ft)[7] long and is sheltered by 30 feet (9.1 m)[7] high jagged cliffs.

Spreading in each direction from the main beach are several small coves, interspersed by rocky outcrops.

The watchtower was built in the mid-16th century[7] to monitor this stretch of the coast for attacks by Barbary pirates coming from North Africa.

The cliffs which back the beach are subject to erosion and it is recommended that great care be taken whilst below as there is a possibility of falling rocks and stones.