Origins and Development
When the fortress and castle were founded, where they were situated and how they evolved over time, are questions to which we are unlikely to find fully satisfactory answers.
The Iron Age settlement area seems to correspond to the northern and southern part of the hill, but we know nothing about the distribution of structures from the days of the Roman Republic or the Roman Empire, or indeed of the period that followed the collapse of the empire.
It is possible that the Islamic settlement on the hill dates back to the 8th century AD and that the existing city was fortified soon after. Largescale construction work took place in Lisbon during the Umayyad period, more specifically in the time of Hisam al-Mu’ayyad bi-lllãh. According to a commemorative inscription dated to 985, these were undertaken by Almanzor. This inscription uses the term madina when referring to Lisbon, which means walled city. Thus, it can be deduced that, at least from the 10th century, the city of Lisbon was protected by a large wall that had been severely damaged and was in urgent need of repair.
Although it is widely accepted that there was a fortified city with a kasbah, there remain many doubts about the existence of a castle and the records left by twelfth-century crusaders and Muslim geographers are silent on this matter.
The oldest references to a castle within the walled perimeter of the kasbah date back to the time of D. Afonso III, the monarch who introduced the principles of active defence in Portugal, which are present in this fortress, and of his son, D. Dinis.
The castle we see today is, without doubt, a gothic castle; it features a quadrangular layout, an elbow shaped gateway, 10 quadrangular turrets attached to the castle wall and a barbican in the more vulnerable south-eastern area, with a thickened base and moat, featuring medieval drawings and inscriptions, and the existence of Albarrana towers.
The fortress underwent extensive modifications over time; transformative buildings work took place during the reigns of King Afonso Henriques (following the conquest of the city), King Afonso III, King Denis (a well-documented period), King Ferdinand, and even during the reigns of King John I and Afonso V. King Manuel and King Sebastian also oversaw extensive modifications to the fortification.
We also have material evidence of the process by which the castle became a residential area, which probably began in the 13th century.
With the union of the crowns in 1580, the castle took on other roles: military base, prison and hospital. Fernando Álvarez de Toledo y Pimentel, Duke of Alba and the Castilian military garrison were stationed here for two years.
The Castle and the Palace were severely affected by the great earthquake of 1755 and, in the period that followed, a large military base was built here. This was later demolished in 1939-1940.