Human presence in the area of Almada dates to the end of the Neolithic period about 5000 years ago; archeological excavations performed in the municipality suggest that non-sedentary nomadic tribes may have occupied this location sporadically.

The gradual development of settlement here made its greatest advance with the coming of Islamic civilization, when Muslims constructed a fort at Almada to defend and monitor the entrance to the Tagus River.

Alongside these Christians there lived many free Moors and Jews, under the royal protection guaranteed them by Afonso I in the charter of 1170 (which applied to all the former Moorish strongholds at Lisbon, Almada, Palmela and Alcácer).

Almada received a foral from King Sancho I in 1190, although it came at a price: Miramolim Jacub-Abu-Jassuf, son of the Moorish leader who had laid siege to Santarém in 1171, was angered by the Christian victories and gathered a large army.

When this event occurred with the success of the Reconquista in driving the Muslims out, the Order of Santiago, a donatorio of Almada after 28 October 1186, had an important role in the territory (especially between the Tagus and Sado Rivers).