One thousand picnickers donned their chicest summer whites and descended on the Art Institute of Chicago’s South Lawn Friday night for Dîner en Blanc, a flash mob-style BYO picnic. Chicago is one of 24 cities worldwide to play host to the hush-hush event, which organizers don’t divulge the location for until just prior to showtime. Our photographer got in on the secret, and snapped these images from a whimsical night of dining, toasting, and dancing.

Photography: James Trevenen