The Musei Capitolini date back to 1471, when Pope Sixtus IV donated to the people of Rome a group of bronze statues that until then had been kept at the Lateran. These statues constituted its original core collection. Various popes subsequently expanded the collection with works taken from excavations around Rome; some were moved from the Vatican, some, such as the Albani collection, were bought specifically for the museum. Around the middle of the eighteenth century, Pope Benedict XIV created a picture gallery. A considerable quantity of archaeological material was also added at the end of the nineteenth century when Rome became the capital of Italy and new excavations were carried out whilst creating two completely new districts were created for the expanding city.
The Museums' collections are displayed in the two of the three buildings that together enclose the Piazza del Campidoglio: Palazzo dei Conservatori and Palazzo Nuovo, the third being the Palazzo Senatorio. These two buildings are linked by an underground tunnel, which contains the Galleria Lapidaria and leads to the ancient Tabularium, whose monumental arches overlook the Forum.
The Palazzo Nuovo houses the collections of ancient sculpture made by the great noble families of the past. Their charming arrangement has remained substantially unchanged since the eighteenth century. They include the famous collections of busts of Roman philosophers and emperors, the statue of Capitoline Gaul, the Capitoline Venus, and the imposing statue of Marforio that dominates the courtyard.
The Conservators' Apartment contains the original architectural nucleus of the building, decorated with splendid frescoes portraying the history of Rome. The ancient Capitoline bronzes on display here add to the noble atmosphere: the Capitoline She-wolf, Spinario and the Capitoline Brutus.
On the first floor of the palace, a huge glass room, recently built, contains the equestrian statue of Marcus Aurelius, which once stood in the Piazza del Campidoglio, and the imposing remains of the Temple of Capitoline Jupiter. A section is also dedicated to the most ancient part of the Campidoglio's history, from its first inhabitation until the construction of the sacred building, displaying the results of recent excavations. The halls that overlook the room contain works from the Horti of the Esquiline; the hall which connects the room to the apartments of the Palazzo dei Conservatori contains the Castellani collection, testimony to nineteenth century collecting practices.
On the second floor, the Capitoline Picture Gallery contains many important works, arranged in chronological order from late mediaeval times to the eighteenth century. The collection includes paintings by Caravaggio (Good Luck and St. John the Baptist), a massive canvas by Guercino (Burial of Saint Petronilla) and numerous paintings by Guido Reni and Pietro da Cortona.
The Palazzo Caffarelli-Clementino holds the numismatic collection, known as the Medagliere Capitolino. On display are many rare coins, medals, gems and jewels, as well as an area dedicated to temporary exhibitions.