This association led to the monastery becoming the richest and most influential in Portugal by 1300, with a population of almost 1,000 monks and business interests including farming, fishing and trade.

Due to its artistic, cultural and historical relevance, it was included in UNESCO's World Heritage Site list in 1989.

The foundation of the monastery was part of a larger strategy by King Afonso I to assert his authority and promote the colonisation of lands recently conquered from the Moors during the Reconquista.

After being crowned king, Pedro commissioned two magnificent Gothic tombs for himself and his mistress, both of which can still be seen inside the monastery church.

[3] During the reign of Manuel I, a second floor was added to the cloister and a new sacristy was built, following the characteristic Portuguese late Gothic style known as "Manueline".

The monastery was further enlarged in the 18th century, with the addition of a new cloister and towers to the church, although the medieval structure was mostly preserved.

The great 1755 Lisbon earthquake did not cause significant damage to the monastery, although part of the sacristy and some smaller buildings were destroyed.

Alcobaça Monastery was classified as a National Monument on January 1, 1907, and included in the special protection zone on August 16, 1957.

Following the precepts of the Cistercian Order, the original monastic buildings were built along lean architectonic lines, without any decoration apart from some capital sculpture and a statue of the Virgin Mary.

This pair of royal tombs in Alcobaça, of unknown authorship, are among the best works of Gothic sculpture in Portugal.

This chapel, located in the south side of the transept, has a sculptural group depicting the "Death of Saint Bernard", one of the best works authored by 17th-century Alcobaça monks.

A relief showing the queen is seen over the tomb, and the sides are decorated with the Apostles under a round arched gallery.

This room, located close to the entrance of the church, has a series of 17th–18th century statues representing the kings of Portugal.

The walls are decorated with blue-white 18th century tiles that tell the history of the Monastery of Alcobaça, since its foundation by Afonso Henriques.

While they ate, one of the monks read aloud passages of the Bible from a pulpit, which in Alcobaça is embedded into one of the walls.

Like the dormitory, the refectory has many pillars separating aisles and is covered by early gothic rib vaulting.

The second floor of the cloister, in Manueline style as revealed by its typical twisted columns, was built in the early 16th century.

Water and fresh fish were diverted from the river Alcoa to the kitchen basin through a specially built canal.