The portico is composed of forty-eight pillars, the whole enclosed in an oblong courtyard about 140 feet by 90 feet, surrounded by a double colonnade of smaller pillars, forming porticos to a range of fifty-five cells, which enclose it on all sides, exactly as they do in a Buddhist monastery (vihara).
It was surrounded on three sides by a series of porticos supported on columns; and these porticos were originally surmounted by a gallery or upper storey, traces of the staircases leading to which still remain, though the gallery itself has altogether disappeared.
Close by to the south is the beautiful Loggia degli Osii, erected in 1316, with two loggie or open porticos, one above the other, in black and white marble.
Traces existing within the exterior porticos on north, west and east indicate much carriage traffic.
The vast size of the market-squares with their surrounding porticos, and the importance of the caravans of merchants who traded with other nations, show that mercantile had risen into some proportion to military interests.