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.

[2] 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.

These reforms in the enclosure were overseen by Wilhelm Ludwig von Eschwege, but likely made the archaeological exploration of the territory considerably difficult.

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

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.

[2] 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).

[2] The castle is located within the limits of the Sintra-Cascais Natural Park, in the north flank of the Sintra Mountains, where the slopes are at most 40% gradients, with accented or moderate variation.

[2] The castle is an irregularly planned military outpost that follows a 450-metre perimeter on top of a mountainous cliff, oriented southwest to northwest.

The Moorish Castle, due to its geographic place and design, was considered, along with Santarém, one of the principal points of the military plan of Belata (the Muslim province which corresponds to the Ribatejo and Estremadura).

The outer walls open near Abelheira (west of Tapada dos Bichos), from a main access door, where several paths wind around the hilltop of the castle.

[5] A small door, normally covered in underbrush, opens to the northern façade of the castle, corresponding to the Traitors Gate, accessing the main "military square" with the structure.

The southern wall is highlighted by an arched doorway, supported by colonnades and decorative capitals, with vegetation or fantastical animal motifs (gryphons and basilisks).

Compared to the city of Lisbon, the castle has cooler temperatures year-round, much less sunshine hours, and more precipitation, humidity and fog.