In 1290 Arnolfo di Cambio built a loggia to serve as the grain market. In 1337 Francesco Talenti, Neri di Fioravante and Benci di Cione began the present structure, which was supposed to be a larger grain market. In 1380 the two upper floors were added to store grain. Only later did it become a church: the loggia arcades were closed off by Simone Talenti and the exterior embellished with Florentine Gothic sculptures and ediculas.
Rectangular in shape, with two naves, inside the church is the imposing Tabernacle by Andrea Orcagna, painstakingly built and decorated in Gothic style between 1355 and 1359.
On the exterior marble tabernacles were built to host statues of the patron saints of the Guilds, who commissioned the greatest artists of the period. Particularly famous are Ghiberti's St. John the Baptist; Verrocchio's St. Thomas.