Instant Classic: Birkenstocks

WHEN YOU HEAR THE WORD BIRKENSTOCK, long-haired, '60s flower children come to mind. But one look at model Andreea Diaconu, who was photographed riding a bicycle in last spring's most-talked-about shoe (Céline's fur-lined Birkenstock), shows the iconic two-strap sandal has gone from granola to glam. In fact, the Birkenstock is no longer just a brand name but a style of its own. Once considered a fashion faux pas reserved for tree huggers, it has been reimagined by the hippest (not hippie-est) of designers—Givenchy's Riccardo Tisci and Giambattista Valli and, of course, Phoebe Philo at Céline—and approved by the industry's elite. From Marni's jet-black beaded number to Lanvin's holograph take, comfort never looked so chic.

FORWARD MARCH

1. Céline's red fur pair stole the street-style spotlight. 2. REBECCA MINKOFF $250; bloomingdales.com. 3. GIVENCHY BY RICCARDO TISCI $600 at Jeffrey New York; (212) 206-1272. 4. MARNI $870; marni.com for stores. 5. LANVIN $990; net-a-porter.com. 6. SAM EDELMAN $80; samedelman.com. 7. CÉLINE $790 at Bergdorf Goodman; (212) 753-7300. 8. GIAMBATTISTA VALLI price upon request at Fivestory; (212) 288-1338. 9. BIRKENSTOCK $195 (available in March); birkenstockusa.com. 10. Model Andrees Disconu in French Vogue, 2013.