San Giovanni dei Fiorentini
is a 17th century minor basilica, parish and titular church dedicated to St John the Baptist, and situated at the north end of the Via Giulia in the rione Ponte. It is also the regional church for expatriates from Florence.
For reference, a plan of the church is available here
Pope Julius II ordered the Via Giulia to be cut through the network of filthy alleys between Via di Monserrat and the river in order to relieve dangerous congestion caused by crowds of pilgrims, and this was opened in 1508. A group of Florentine expatriates, including the Florentine Pope Leo X de Medici, decided to build a magnificent church on a prime site at the north end of the new street. The first architect ran into trouble with the foundations at the river end. A new architect, Antonio da Sangallo the Younger, a military engineer as well as an architect, succeeded with the foundations but did not manage to complete the church. Construction ground to a halt by the time of the Sack of Rome in 1527.
In 1583 Cardinal Ferdinando de'Medici assigned the church to Giacomo della Porta who built the S_pics between 1583-92 on the extant substructure, based on the Latin cross arrangement. After his death in 1602, the building passed to Carlo Maderno took over from 1602-1620 during which time the dome was constructed and the main body of the church completed. The last part to be completed was the present façade, by Alessandro Galilei from a commission by Pope Clement XII , who died the year before its completion.
An extensive restoration took place in 1853, including floor, under the direction of Gaspar Salvi. In 1918 it was made a minor basilica. In 2001, a new museum was opened. In 2006 a copy of the icon of Our Lady of Altagracia, venerated in the Dominican Republic, was blessed for the church.