THIS IS ONE RUST BELT town that's gotten a polish. After decades of losing jobs and residents, Pittsburgh has become a standard-bearer for urban revitalization.

Joining its distinctive, bridge-studded skyline are ambitious buildings like the modernist Tower at PNC Plaza, expected to open in 2015 as the world's greenest skyscraper, and the Gardens at Market Square, a $90 million high-rise. Downtown is undergoing a gold rush, with old factories and closed department stores being converted rapid-fire into apartments and spaces...