The Moorish Castle in the fog, overlooking the historic town of Sintra

The castle was constructed during the 8th and 9th centuries, during the period of Muslim Iberia, as the central place in a territory that was primarily agricultural, and which was necessary to protect its population.[1][2][3]

In 1031, after the loss of Córdoba to the Almoravid dynasty, the king of Badajoz opted to transfer to Alfonso VI of León and Castile a few territories on the Iberian peninsula (among them Sintra) in order to gain an alliance with the Christian king.[1] This transfer did not result in any security, and the castle was lost to the invading Almoravid.

After the conquest of Lisbon (1147) by forces loyal to Afonso Henriques, the castle surrendered voluntarily to Christian forces.[1][4] Afonso Henriques entrusted the castle's security to 30 inhabitants, granting them privileges in the foral (charter) signed by the monarch in 1154.[1][4] The charter suggested that settlers should occupy and inhabit the castle, as a mechanism for guaranteeing the region's security and development.

During the second half of the 12th century, the chapel constructed within the walls of the castle became the parish seat.[1] This was followed by the remodelling and construction under the initiative of King Sancho I of Portugal.[1]

In 1375 King Ferdinand I of Portugal, under the counsel of João Annes de Almada, ordered the rebuilding of the castle.[1] While the structure was well fortified by 1383, its military importance was progressively diminishing as, more and more, the inhabitants were abandoning the castle for the old village of Sintra.

While the chapel was still being used a centre of religious activities at the beginning of the 15th century, by 1493 this chapel was abandoned and later only used by the small Jewish community of the parish.[1] This was followed in the 16th century by the transfer of the ecclesiastical parish of São Pedro from the castle to the new parochial church in the village. The Jews occupying and using the structures in the castle were expelled by Manuel I of Portugal, and the castle was completely abandoned.[1]

The 1755 Lisbon earthquake caused considerable damage to the chapel and affected the stability of the castle. Visiting the chapel, Francisco de Almeida Jordão described the chapel (in 1768) as having a "principal door in the east, and in the south another smaller door, and a window...An addition to a painted image on the altar, there was another of rock which, already exists in the hermitage of Santa Eufémia, where they took it".[1][5] An 1830 lithograph by Burnett immortalized the chapel's place in the Castle.[1]

By 1838 the towers were already in ruins, when in 1840 Ferdinand II of Portugal took up the task of conserving and improving the condition of the castle, in which he committed 240 réis annually.[4] He consolidated the walls, reforested the spaces, created nooks and manicured spaces and conserved the chapel.[1] Along the south flank of the chapel he built a monument to collect the bones discovered during the public works, planting a tree in the central nave of the chapel. These reforms in the enclosure were overseen by Wilhelm Ludwig von Eschwege, but likely made the archaeological exploration of the territory considerably difficult.[4]

At the end of the 19th century the administrator of the Forestry Service, Carlos de Nogueira, authorized several projects in the castle and chapel.[1]

In 1939 the DGEMN became involved in the reconstruction of the castle walls, in addition to the lateral door of the chapel.

 

Part of the reconstructed wall viewed from the bottom.

With an eye towards a fledgling tourist market, in 1954 a few of the cliffs were cleared to establish a picnic area near the castle, and in 1965 a transformer was installed to provide illumination.[1]

In 1979 archaeological excavations in the Chapel of São Pedro were begun by the cultural services of Portugal, which discovered the existence of medieval funerary tombs, dating to the turn of the 13th century.

A dispatch by the Ministry of Culture, on 26 June 1996, declared the area of the Castle as a zone of special interest (Portuguese: Zona Especial de Protecção do imóvel).[1]

During the summer of 1986, scouts were involved in projects to consolidate the walls with cement and clean the grounds, supported by the CMS.[1]

In 2001 there were various interventions associated with cleaning the property, clearing undergrowth and forest overgrowth, and the installation of an electrical box along one of the walls.[1]

 

Panoramic view from atop a castle wall in 2019, showing the highest point of the castle in the distance right of center, and Sintra in the valley below