Castelo dos Mouros, also known as the Castle of the Moors, is a historic castle located in Sintra, Portugal. The castle dates back to the 8th or 9th century, during the period of Islamic rule in the Iberian Peninsula. It was built on the Sintra Mountains and served as a strategic military fortress for several centuries.

The castle is located on a rocky outcropping and was designed to provide a commanding view of the surrounding area. It consists of a series of walls and towers that follow the contours of the hill, forming a formidable defensive position. The walls are made of granite blocks and are several meters thick in some places. The castle is also surrounded by a moat, which provided additional protection against enemy attacks.

The Castle of the Moors played an important role in the history of Portugal. In the 12th century, it was conquered by the Christian forces of Afonso Henriques, the first king of Portugal. Over the centuries, it fell into disrepair and was largely abandoned until the 19th century, when it was restored by King Ferdinand II.

Today, the Castle of the Moors is a popular tourist destination, with visitors coming to admire its impressive architecture and sweeping views of the surrounding countryside. The castle is a UNESCO World Heritage Site and is considered to be one of the most important historic landmarks in Portugal.