The first historical reference to the Almada region dates back to the Neolithic period, around 5 thousand years ago. This was a transit point for communities such as the Romans, Phoenicians and Carthaginians, but it was the Arabs who ended up exerting the greatest influence in the region.

Its location on the northwestern tip of the Setúbal Peninsula, on the banks of the River Tagus and opposite Lisbon, made it a strategic military point for the defense and surveillance of the region's trade routes over the years. The Tagus River was a crossroads for vessels that exchanged goods such as flour, fruit, fish, wine, etc. Almada (notably Cacilhas) was one of the main ports of the Iberian Peninsula.

In the Middle Ages, in 1147, Afonso I of Portugal, with the help of the crusades from northern European countries, conquered Almada, one of the main Arab military bases south of the Tagus.

Later, in 1170, Afonso I of Portugal granted it to the Moors who helped in the conquest and repopulation of the region. They held control until Sancho I of Portugal conquered it in 1186 and attributed it to the Order of Santiago.

In 1190, Sancho I of Portugal granted the first extensive charter to Christians and free men who lived in the town and its surroundings. This first charter remained practically unchanged until the 16th century.

On December 1, 1297, King Dinis negotiated with the Order of Santiago and incorporated Almada into the Crown's Assets in exchange for other towns south of the Tagus. The first official delimitation of the municipality's territory, which roughly covered the current municipalities of Almada and Seixal, dates from this exchange.

In 1384, during the Interregnum, Almada was besieged by the Castilian troops of John I of Portugal of Castile. The population takes refuge within the walls of Almada Castle where, prevented from accessing Fonte da Pipa (the main source of drinking water), they find themselves weakened by thirst: the residents are forced to drink their own urine and knead bread with wine. Almada ends up surrendering.

In 1513, Manuel I of Portugal grants Almada a new Charter, which brings about economic, social and political transformations. The first references to the population and parishes of Almada began to be recorded in cadastral documents. The Almada Term acquired significant importance during the Portuguese maritime expansion, being an integral part of Lisbon's economic influence zone.

The 1755 earthquake caused great damage in Almada. Almost all the noble houses collapsed, as did the houses of the people. Thousands of people were killed, injured or left homeless. The monumental heritage with centuries of history also collapsed.