The heir to the Chigi family, Pope Alexander VII built this palace which is one of the most important around Piazza Colonna. The founder of this great family was Agostino Chigi who moved from Siena to Rome at the end of the 15th century.

He became one of the key figures in the political, economic and social life of the city and was responsible for Villa Chigi, the extraordinary Villa Farnesina as it is known today.
The family went into long decline after his death, but Alexander VII returned it to its previous splendor. Two years after his election, the Pope chose one of the most sought-after districts of the time for his family residence and bought this palazzo while it was still being built from the Aldobrandini family.
The building was eventually acquired by the Italian State and, after 1961, became the seat of the Presidency of the Council of Ministers, in other words, the office of Italy's Prime Minister.