It was a city of compounds. Some of these dated back to the early days of its construction, when the bubble had not yet been completed and there had been a need to make smaller inflatable domes over certain areas. Others had been built in imitation of those first ones. Neither the compounds—which, for structural reasons, tended to be circular—nor the overall topography lent themselves to a grid street pattern. Consequently the map was a chaos of switchbacks and meanders and streets that turned suddenly into stairways or tunnels. Limitations on building height led people to dig down into the underlying metal, rather than building upward, and so most of the city’s square footage was hidden. The buildings were like icebergs, larger below than above.