These courts often had an impluvium, or fountain, to catch rainwater from the roof, as well as furnishings for outdoor entertaining. Hence the atrium, which has its own storied architectural history: Ancient Roman houses were centered on open-air or skylit spaces, which provided daylight and breezes to the rooms surrounding them. But by the early 1970s, and the advent of more complexly laid-out malls in T-, X-, or O-shapes, patrons might wander forever, missing each other in the long, low-ceilinged identical halls. The earliest indoor shopping malls, with their I-shaped, bowling-alley forms, had no centralized place where groups could gather, nor much need for one. Is my friend hanging out at the mall? Is my crush? This is the atrium, the most important interior space of the mall for the adolescent both architecturally and psychologically. Escalators traveling between floors make for easy, surreptitious people-watching.

If the mall is multilevel, skylights illuminate the space from above. A stepped, centralized seating area appears, in one form or another, in most malls built in the 1980s.