Some of the major vestiges of the Ancient Rome are located in the area, such as the Palatine Hill, the Campidoglio and the Roman Forum.

The Palazzo Senatorio and the basilica of Santa Maria in Ara Coeli are the only remaining features of the medieval construction industry in the rione.

The rione experienced relevant urban modifications between 1536 and 1546, after Pope Paul III commissioned to Michelangelo the refurbishment of the Campidoglio and of the nearby piazza, to receive Emperor Charles V. Michelangelo's project was brought to completion only in 18th century by Carlo Rainaldi, who built the baroque church of Santa Maria in Campitelli.

The appearance of the area changed relevantly between 19th and 20th century, after the construction of the Victor Emmanuel II Monument and after the massive demolitions performed by the Fascist government.

To the west, the rione borders with Sant'Angelo (R. XI), whose border is marked by Via del Teatro di Marcello, Via Montanara, Piazza di Campitelli, Via Cavalletti, Via dei Delfini, Piazza Margana, Via Margana and Via d'Aracoeli.