Seat of the Chamber of Commerce, Industry, Agriculture and Crafts, Palazzo della Mercanzia has managed the Bologna trading and business activities since the late 14th century. The construction of the Carrobbio open gallery (now the Mercanzia) began in 1348 under the direction of Antonio di Vincenzo and Lorenzo Bagnomarino with the purpose of merging three buildings previously used as customs and toll house. Four stonecutters from Florence were called to build the gallery and prepare the natural stone.
The building was completed in 1391, but the elegant construction needed an extension in 1439 and restoration work in 1484 following the collapse of the de' Bianchi tower. In 1888-90, it was renovated under the direction of Rubbiani and Tartarini. It was then rebuilt in 1949 after an unexploded bomb set off nearby led to the collapse of half of the façade. The façade is made of brick and Istrian stone and features two deep Gothic arches that make it seem taller, an effect also obtained thanks to the porch floor, which is raised from the surrounding square.
A small marble balcony juts out between two mullioned windows above the arches, from which the judges of the merchants' court would read their sentences. An elegant spire rises above the balcony covering one of the dovetail merlons at the top of the building. According to local tradition, bans and sentences of the merchant's court were read out from this marble canopy at the stroke of the bell called "Lucardina".
The culprits of fraudulent bankruptcy were instead chained to a post placed before the central pillar of the gallery to be derided. Despite the changes the building has endured over time, the rooms and ambulatories still maintain the beauty of their masterpieces unaltered.
In the early 15th century, a plaque commemorating the exemption from duties granted to students at the University of Bologna was affixed on the wall in Via Castiglione. It reads: The privileges according to which students mustn't pay for books and other everyday use object such as supplies and clothing have been confirmed by Citramontani Dean Giuliano de' Davanzati and Ultramontani Vice-Dean Pietro di Poggiomarino di Catalogna.