One of the first Cistercian monastic foundations in Portuguese territory, the Alcobaça Monastery became the main house of this religious Order, thanks to a continued policy of royal protection, initiated by the first king of Portugal, D. Afonso Henriques. 

The preserved medieval rooms make the Alcobaça Monastery a unique complex in the world, adding up to the later buildings, from the 16th to the 18th centuries, important testimonies of the evolution of Portuguese architecture. It is inscribed on the UNESCO World Heritage List since 1989.

The foundation of the Abbey of Santa Maria de Alcobaça and its Religious Charter date from April 8, 1153. The domains of the Cistercian Order were thus consecrated. The domains of the Kingdom of Portugal, after the conquest of the cities of Santarém and Lisbon in 1147 expanded towards the Tagus Line in the south. This required rapid and effective settlement for Christian expansion to continue southward. The protection of the religious locations was entrusted to the militia of the Order of the Temple, exempting them, as much as possible, from the military onslaughts of the Moors. The focal point was the abbey itself. Its construction began in 1178. This date is shrouded in great strategic significance: four years later, Saint Bernard was canonized. This was most probably one of the first abbeys of the Order to be built with this intention.

The importance of the Alcobaça Monastery evolved in cultural, religious and ideological crescendo. The more simple and clear the architecture, the more evident its grandeur becomes. It is the first example of Gothic architecture in Portugal, and while it had no immediate successors and was later reproduced, served as a unique landmark in the landscape. as an almost isolated pole, a white jewel in the landscape.