It was a meeting place for the local nobility and a privileged trading post, equipped with a public weighbridge, from the end of the 17th to the 18th century. Here the ration officers set the prices of food on a weekly basis and verified the correct use of the weights and special measures in force in the State of Gradisca to avoid fraud.

later, in the 19th century it was transformed into a home and shop. Recovered and once again used for a public function, from 1939 the loggia was dedicated to house the civic epigraphical museum on the ground floor.

The Loggia dei Mercanti was built in 1688 by Count Francesco Ulderico della Torre (for this reason also called Loggia Torriana), as evidenced by the epigraph painted inside the loggia. Under it there is also a fresco of the crucifixion of Christ. The building was erected on a pre-existing Venetian loggia (1488), so that this construction, like the others from the same period, is based on the “Venetian step” module (1.73 m).

The building presents an unusually vertical projection, considering that in Gradisca almost all houses have a flat and elongated development. With a rectangular plan, on three levels, the building features a large loggia on the ground floor, which is accessed through three arches with ringed columns preceded by a staircase. On the wrought iron gates there are the coats of arms of the city and the della Torre family.

The civic epigraphic museum is housed on the ground floor of the Loggia dei Mercanti. It preserves tombstones, epigraphs and other stone material found in Gradisca and its surroundings, collected mainly by Valentino and Ettore Patuna. The stones, from different eras, help to tell the story of the city, in particular of its foundation.

The most important stone mentions the foundation of the fortress of Gradisca by the Republic of Venice in the second half of the 15th century: a new fortress - designed to defend the eastern border from Turkish incursions - which takes its name from the already existing village. The first administrator of the city is Francesco Tron.

The construction work of the fortress lasted several years and involved many personalities, who had their merits carved in stone. An inscription recalls that in 1479, under Doge Giovanni Mocenigo, the fortifications were strengthened by the lieutenant of Friuli Giovanni Emo.

He built walls and moats and the work was entrusted to Enrico Laufer of France, known as Gallo, who named the new fortified citadel Emopoli in his honour.

The lapidary also preserves coats of arms from the Venetian and archducal periods, as well as tombstones. Among the latter, that of captain Francesco Ulderico della Torre, coming from the church of the Serviti.