Vatican City, independent state within Rome, Italy, that is ruled by the pope and serves as the world headquarters of the Roman Catholic Church. Entirely surrounded by Rome, Vatican City is the smallest country in the world, with an area of 44 hectares (110 acres).
Saint Peter’s Basilica

Vatican City occupies a triangular area on Vatican Hill in northwestern Rome, just west of the Tiber River. Except at Saint Peter’s Square (Piazza San Pietro) on its southwest flank, Vatican City is surrounded by medieval and Renaissance walls that separate it from the city beyond. Within its walls is a vast complex of courtyards, gardens, and magnificent buildings, the largest and most imposing of which is the great domed Saint Peter’s Basilica—the principal church of Roman Catholicism.