The Basilica del Pilar, or Holy Metropolitan Temple of Our Lady of Pilar, is one of the two cathedrals of the Archdiocese of Zaragoza, along with the Seo del Salvador. According to tradition, it is considered the first Marian temple of Christianity, since in its interior is preserved a pillar of jasper that, supposedly, the Virgin Mary placed in the year 40 when she appeared to the apostle Santiago. However, this story does not have documentary evidence until the end of the 13th century.

The documented history of the temple begins in the 9th century, when there was a Mozarabic church dedicated to Santa María, around which a Christian community was formed.

The present basilica, in Baroque style, is composed of three naves of equal height covered by barrel vaults and domes resting on solid pillars. The building follows the Aragonese tradition of brick construction and the interior is covered in stucco. Among its most outstanding elements are the main altar with its Renaissance altarpiece made by Damián Forment in the 16th century, the Holy Chapel of the Virgin and the choir, from the old Gothic church.

Since 1676, El Pilar has held the rank of cathedral and, in 1948, received the title of minor basilica by Pope Pius XII. It is part of the Marian Route, along with other emblematic sanctuaries, and in 2007 it was recognized as one of the 12 Treasures of Spain.