Alcobaça (əlkŏbäˈsə) [key], town (1991 pop. 5,235), Leiria dist., W central Portugal, in Estremadura. The town, a fruit processing and textile center, became a center of the Cistercians in the reign of Alfonso I, and its abbey (building begun 1152) was the greatest of medieval Portugal. The Alcobaça Cistercians exercised enormous influence on education, social conditions, finance, and politics. The early kings of Portugal are buried in the abbey.