ENGINEERS, POLITICIANS, AND business owners have anguished for years over how to juggle tearing down the old waterfront viaduct and building whatever we wind up putting in its place—and how much of the waterfront will be shut down as a result. Their counterparts in 1907 didn’t fret so much. When the city decided to lower and level Third Avenue—one in an epic series of terrain-transforming regrades—it didn’t bother shutting down the Madison Street cable car. Crews just levitated the tracks on wooden scaffolding, and day-trippers and cottage owners could still escape to Madison Park, then a bucolic lakeside retreat.