Serra d'El-Rei ('Mountains of the King') is a Portuguese parish in the municipality of Peniche on the Atlantic Coast. The population in 2011 was 1,401, in an area of 8.92 km². Serra d'El-Rei became a town on July 1, 2003.

It was at Serra d'El-Rei that King Peter I of Portugal lived with his lover Inês de Castro. His 14th-century castle in the town is now divided into three private living houses today.

Serra d'El-Rei is 7 km (4.3 mi) west of the historic walled-town of Óbidos, and 10 km east from Peniche.

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  The 17th century Catholic church in the town square
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  Interior of the church showing typical hand-painted blue and white tiles with Biblical scenes

• Serra d'El-Rei official website