The Papal Basilica of Saint Mary Major (Italian: Basilica Papale di Santa Maria Maggiore, Latin: Basilica Sanctae Mariae Maioris), known also by other names, is the largest Roman Catholic Marian church in Rome, Italy. There are other churches in Rome dedicated to Mary, such as Santa Maria in Trastevere, Santa Maria in Aracoeli, Santa Maria sopra Minerva, but the greater size of the Basilica of Saint Mary Major justifies the adjective by which it is distinguished from the other 25.

According to the 1929 Lateran Treaty, the basilica, located in Italian territory, is owned by the Holy See and enjoys extraterritorial status similar to that of foreign embassies. The building is patrolled internally by police agents of Vatican City State, not by Italian police.