The Cathedral of St Peter the Apostle (Spanish: Catedral de San Pedro Apóstol) is the cathedral church of the Roman Catholic Diocese of Jaca located in Jaca, in Aragon, Spain. It is the first Romanesque cathedral built in Aragon (1070s-early 12th century) and one of the oldest in the Iberian peninsula. Its current appearance is the result of later additions and modifications introduced especially in modern times (late 15th-late 18th centuries). The cathedral was erected by will of King Sancho Ramírez, who, after renovating in Rome his vassal oath to the Pope (1068), had obtained by the latter the right to establish the episcopal seat in Jaca, then capital of the Kingdom of Aragon.