Downtown Chicago may be renowned fo...

Downtown Chicago may be renowned for its architecture, however art and commerce have traditionally kept their distance from each other along glitzy North Michigan Avenue.

Tension between the pair is beginning to show. Arguably the city's mostly celebrated thoroughfare, Michigan Avenue lately landed on the Landmark Preservation Council of Illinois' (LPCI) list of the state's 10 most-endangered historic sites.

The straw that broke the camel's back? "With preservation, there's at no time a final straw," observed LPCI executive director Ron Emrich. "It's usually a portion of little ...