Alcobaça () is a Portuguese city and municipality in the Oeste region, in the historical province of Estremadura, and in the Leiria District. The city grew along the valleys of the rivers Alcoa and Baça, from which it derives its name. The municipality population in 2011 was 56,693, in an area of . The city proper has a population of 15,800 inhabitants. The city of Alcobaça became notable after the first king of Portugal, Afonso Henriques, decided to build a church to commemorate the Conquest of Santarém from the Moors in 1147. The church later evolved into the Monastery of Alcobaça, one of the most magnificent gothic monuments in the country. In the church are the tombs of Pedro I of Portugal and his murdered mistress Inês de Castro. Over the centuries this monastery played an important role in shaping Portuguese culture. A few kilometers to the north of Alcobaça is the Monastery of Batalha, another gothic building constructed in memory of a different important battle, that of Aljubarrota. To the west of Alcobaça is the fishing village of Nazaré, now a popular resort town. To the south is the city of Caldas da Rainha and the medieval town of Óbidos. Also to the northeast is the town of Porto de Mós with its rebuilt castle. History A town that only became notable in the 12th century when it was chosen as the future site of Portugal's largest church. In March 1147, the fledgling King Dom Afonso Henriques, defeated the Moors by capturing the city of Santarém. As a tribute to his victory he vowed to build a magnificent home for the Order of Cistercians. It took another 76 years before this task was completed. The monarchy continued to carry out further construction and 60 years later King Dinis built the main cloister. The Monastery was consecrated in 1262. The church contains the tombs of Pedro I of Portugal and his murdered mistress Inês de Castro and with it the story of the tragic liaison between Pedro and Inês. Forced at an early age as a royal duty, he was to marry Constanza, the Infanta (Princess) of Castile, but died shortly after the marriage. Dom Pedro escape with his true love and later lived in the city of Coimbra. His father, King Afonso IV, believing that the family of Inês was a threat to his own kingdom had her murdered.