Documents from 1067 cite a church of "San Martino in Guazzolongo" (name of the quartiere), belonging to the Augustinian order.

It was rebuilt in 1331, under the commission of Bonifacio Novello della Gherardesca, who wished to endow nuns of an Order of Saint Clare a convent.

The polychrome ceramic baptismpal font is now found in the Museo Nazionale di San Matteo.

The Marble facade has a copy of the bas relief of San Martino and the poor man attributed to Andrea Pisano; the original is kept inside.

The church contains the funeral monument of Marchese Francesco Del Testa by Giovanni Antonio Cybei with a portrait in marble relief (1780).