ambulacrum : am-bu-LAH-krum

(Latin; pl. ambulacra: curved corridor or passageway). The cavea (seating area) of a Roman theatre or amphitheatre featured a system of barrel-vaulted corridors that facilitated spectator circulation and access. These curved passageways are the ambulacra. There were typically two types: outer ambulacra that ran around the perimeter of the structure, and inner ambulacra that were integrated within the substructure itself. The term derives from the Latin ambulare meaning “to walk,” reflecting their essential function as circulation spaces that enabled the efficient movement of large crowds during performances and events.