According to tradition, Gian Lorenzo Bernini was responsible for the design of the square well staircase in the expansion project of the Sforza palace, bought by the Barberinis in 1625 to be used as the main residence of the family. Contrasting with the helical one by Francesco Borromini, both in terms of position inside the building and stylistic setting, Bernini's project had to take into account a more complex articulation of levels because it was inserted in the pre-existing northern wing of the Sforza building. Starting from the lowest floor, the staircase had to connect the main entrance on the courtyard of the Cavallerizza (destroyed in the twentieth century for the creation of via Barberini) with the already existing staircase that led to the garden level and then go up to the main floor, and to the superior. Bernini managed to overcome the difficulties by emphasizing the monumental proportions and the courtly style required by the client.