Thirty years ago, the French considered collecting even 19th-century antiques to be avant-garde. But in this new 21st century, Parisian taste has whizzed fast forward. In the antiquaire stronghold of the Carré Rive Gauche, the rue de Lille has metamorphosed into Modernist Row. A stroll reveals finds such as an Art Nouveau cabinet, chic 1940s jewelry, and a pair of 1970s suede-covered oak and polished steel commodes (€15,000)...