The Romans, who ruled and colonized the territory of current-day Portugal for more than four centuries, built forts with high walls and strong towers to defend their populations.
Portugal has well-defined geographic boundaries, with the Atlantic Ocean to the south and west, and rivers and mountains to the east and north.
The Tagus basin divides the nation in half, with the yellow hills and cattle fields of the central region on the north bank and the beginnings of the Alentejo to the south.
The Romans, who occupied Portugal for the next 400 years after this period, then built forts with high walls and strong towers to defend their towns.
Eventually, the Romans gradually built their centers based on their trade and/or commercial needs and abandoned many sites for places along rivers or lowland agricultural settlements.
By the Middle Ages, Portugal was a crossroads of cultures, with hostile Moors to the south and rival Iberian kingdoms to the east.
Built between the 8th and 13th centuries, the castle retains its walls and square-shaped towers from the Moorish period (including its 11th-century cisterns or water reservoirs).
During the Portuguese Reconquista (12th and 13th centuries) many of the castles were reused or rebuilt to protect their fledgling kingdom from invasions from both Moors and rival Christians, like the Castilians.
Around the 12th century, Portugal emerged as a nation led by the nobleman Afonso Henriques, launched a bold crusade to carve the southwestern half of the Iberian Peninsula away from the Moors.
During the Gothic period, the castles became more and more flamboyant and deadly, with archers’ loops in the castellated walls, oil spouts at the base of parapets, and increasingly higher keeps and towers.
The 13th and 14th centuries was a period of flamboyant castle building, with more decorative touches and features, like pepper pots on towers, ornate brickwork, and massive great halls built of stone.
Gone were high walls, proud keeps and strong towers, transitioning into low stonewalls built around mounds of earth to repulse cannonballs.