Originally it was part of a group of hills that included Collis Latiaris, Mucialis (or Sanqualis), Salutaris. These are now lost due to buildings built in the 16th century and following.
According to Roman legend, The Quirinal Hill was the site of a small village of the Sabines, and king Titus Tatius would have lived there after the peace between Romans and Sabines. These Sabines had erected altars in the honour of their god Quirinus (naming the hill by this god).
Tombs have been discovered from the 8th-7th centuries B.C. that could confirm a likely presence of a Sabine settlement area; on the hill there was the tomb of Quirinus, that Lucius Papirius Cursor transfomed into a temple for his triumph after the third Samnite war. Some authors consider it possible that the cult of the Capitoline Triad (Jove, Minerva, Juno) could have been celebrated here well before than in Capitolinum. The sanctuary of Flora, an Osco-sabine goddess, was here too.
In 446 BC, a temple was dedicated on the Quirinal in the honour of Semo Sancus Dius Fidius, and it is possible that this temple was erected over the ruins of another temple. Augustus, too, ordered the building of a temple, dedicated to Mars.
In the Middle Ages the Torre delle Milizie and the convent of St. Peter and Domenic were built, and above Constantine's building was erected the Palazzo Rospigliosi; the two famous statues of the Dioscuri with horses, which now are in the Quirinal's square, were originally in this Palazzo. In the same palazzo were also the two statues of river gods that Michelangelo moved to the steps of Palazzo Senatorio on the Capitoline Hill.
In 1574 Pope Gregory XIII started the building of a summer residence, in an healthier area than the Vatican Hill or Lateran, by the architects Flaminio Ponzio and Mascherino; under Pope Sixtus V works were attended by Domenico Fontana and Carlo Maderno, and Gian Lorenzo Bernini for Pope Clement XII. Gardens were conceived by Maderno. The Palazzo del Quirinale was the residence of the popes until 1870, when Rome was conquered by the kingdom of Italy; it became the residence of the kings until 1946.
The Quirinal Hill is today identified with the palazzo del Quirinale, the official residence of the President of the Italian Republic and one of the symbols of the State.
The Palazzo hosts the offices and the apartments of the Head of State, and in its long side along via XX Settembre (so-called Manica Lunga), the apartments that were appositely arranged, decorated and furnished for each visit of foreign monarchs or equivalent authorities. Several collections are in this Palazzo, among which arazzi, paintings, statues, old vehicles (carrozze), watches, furnitures, porcelains. See  (in italian only).
The hill hosts several other important monuments.