The first nucleus, a collection of ancient sculptures, was constituted by Julius II (1503-13) but the idea of the museum was born with Clement XIII (1758-69), who with the assistance of Winckelmann had the Museo Profano exhibiting set up Greek and Roman sculptures. With Clement XIV (1769-74) and Pius VI (1775-99) the Museo Pio Clementino was born, which brings together the most famous examples of ancient sculpture such as the Apollo del Belvedere, the Laooconte group and the Torso del Belvedere, while in 1807 -10, under Pius VII, the Chiaramonti Museum is set up by Canova, which houses Roman sculptures.
In 1822 the Braccio Nuovo is opened with over 150 sculptures including statues such as the wounded Amazon, the Doryphoros, the enormous statue of the Nile, the Augustus of Prima Porta. With Gregory XVI the Gregorian Etruscan Museum was opened in 1837 , with finds coming mostly from the nineteenth-century excavations carried out in southern Etruria, and in 1839 the Egyptian Gregorian collecting a series of statues depicting deities or characters of the royal family, sarcophagi, mummies and elements of funerary furniture. In 1844 he opened the Lateran Profane Museum (today Gregoriano Profano) and later the Pio Cristiano which collected materials from excavations in the Roman catacombs including numerous sarcophagi.
https://www.turismoroma.it/it/node/121