The Cathedral of St Peter the Apostle (Spanish: Catedral de San Pedro Apóstol) is a Roman Catholic church located in Jaca, in Aragon, Spain. It is the seat of the Roman Catholic Diocese of Jaca. 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 the early modern period (from the late 15th to late 18th century). The cathedral was erected on command of King Sancho Ramírez, who, after renovating in Rome his vassal oath to the Pope Alexander II (1068), had obtained from the latter the right to establish the episcopal seat in Jaca, then capital of the Kingdom of Aragon.