Located within Rome, Vatican City is the smallest state in Europe and in the world. It is a roughly triangular area of 0.44 sq km(0.17 sq mi) lying near the west bank of the Tiber River and to the west of the Castel Sant'Angelo. On the W and S it is bounded by the Leonine Wall. The Vatican area comprises the following: St. Peter's Square, enclosed by Giovanni Lorenzo Bernini's quadruple colonnade; St. Peter's Basilica, the largest Christian church in the world, to which the square serves as an entrance; a quadrangular area north of the square in which there are administrative buildings and Belvedere Park; the pontifical palaces, or the Vatican proper, lying west of Belvedere Park; and the Vatican Gardens, which occupy about half the acreage.
Outside Vatican City itself, extraterritoriality is exercised over a number of churches and palaces in Rome, notably the Lateran Basilica and Palace in the Piazza San Giovanni, the Palace of San Callisto at the foot of the Janiculum hill, and the basilicas of Santa Maria Maggiore and San Paolo fuori le Mura. Extraterritoriality outside the city of Rome extends to the papal villa and its environs (almost 40 hectares/100 acres) at Castel Gandolfo, 24 km (15 mi) SE of Rome, and to the area (about 420 hectares/1,040 acres) at Santa Maria di Galeria, some 19 km (12 mi) N of Rome, where a Vatican radio station was established in 1957.