In the past this square used to be called "Piazza del Cassero" because it occupied the large area, surrounded by walls, next to the ancient fortress.
The name "Piazza Garibaldi" was decided with a resolution by the City Council dated June 15, 1882 to commemorate the hero Giuseppe Garibaldi, who had died a few days earlier. The name of the square also aims to remember his arrest, which occurred on September 24, 1867 in the house of the Agnolucci family, while he was approaching the border of the Papal State, in an attempt to reunite Rome with the Kingdom of Italy.
On the occasion of the 150th anniversary of the Unification of Italy in 2011, a mural by the workshop of Master Federico D'Agostino depicting the arrest of Garibaldi was painted on the external wall of a building at the crossroads between the square with the same name and via Cavour.
During the same City Council of 1882 it was also decided to hold the village market in this square every Tuesday of each week. It is one of the largest in the Valdichiana and it still takes place today.
In this square there are also some important political and religious institutions, such as the Town Hall, and three churches: the Collegiate Church of San Martino, the Church of Madonna delle Nevi and the Church of Santa Croce.
This square has always been an important place to get together and socialize, a meeting point for the gossip of the village and long-lasting card matches, but also a place for heated arguments about politics and sports, as well as a setting for lively events, such as the Incantaborgo, which takes place every year in July.
Finally, every year on the Sunday closest to November 11, in Piazza Garibaldi the "Corsa dei Carretti" takes place - an event in which the nine districts of Sinalunga compete against one another using race carts to win the palio devoted to the town's patron saint San Martino.