The first sight is unforgettable. All of the way in from the airport the city is held invisible, blocked out by a long, sweeping curve leading down into a tunnel. The [tunnel] traffic slows to a crawl; white walls close in, claustrophobic. When at last I break free into light, the city is all around me and I am locked in a circle of cliffs.

Three great rivers—the Allegheny, the Monongahela and the Ohio—merge at the tunnel’s end, and each is banked by range upon range of bluffs. Rows of squat white houses cling to the wooded hillsides, defying gravity. Across a vaulted bridge, the downtown skyscrapers rise sheer from the waterfront, a city of precipices.