Buitrago del Lozoya (Spanish pronunciation: [bwiˈtɾaɣo ðel loˈθoʝa]) is a municipality of the autonomous community of Madrid in central Spain. It belongs to the comarca of Sierra Norte. The town is one of the few in the community that have maintained its walls, which are of Moorish origin (11th century) and have been restored in the 15th century.