Hidden within its walls, is the core of the original medieval llotja known as the saló de Contractacions, one of the finest civil gothic buildings in the Mediterranean.

Originally conceived to provide merchants with a place for commercial transactions, it has also been used as a wheat store, an entertainment space, as a weapon magazine, a military barracks and the seat of the Consulate of the Sea and the Royal Barcelona Board of Trade.

As commercial activity expanded, Pere Llobet built a porch (or loggia) between 1352 and 1357 practically on the beach near the port, possibly on the location of a previous building used by merchants in what was called plaça dels Canvis lit.

The building has a height of 22 meters and its facades are topped by 4 pediments whose importance is demonstrated by its location, opposite the Palace of the Viceroy and to its side, the sea wall and its gate called the Portal de Mar (long before Passeig d'Isabel II was built).

[4] The gothic Llotja de Barcelona can be considered the first mature example in the Crown of Aragon of a type of architecture that became common for mercantile activity and is more elaborate in design than any other contemporary (late 14th century) such building.

The Contracting Hall is 14 meters high, with three naves separated by semicircular arcades with 4 columns and 6 arches that support the wooden ceiling and the upper floor.

On the spandrels of the arches, you can see the coats of arms of the king and the city alternating since the construction of the building was promoted by Peter IV of Aragon and the Consell de Cent.