The cryptoporticuses of Arles consist of three U-shaped galleries with a width of almost 33 ft (10 m). The north and south galleries that form the two branches of the U open to the east extend over 295 ft (90 m) and are connected by a 196 ft (60 m) gallery to the west. Each branch of the U is composed of a double gallery with two parallel barrel vaults that fall on a series of lowered arches.