This super-secret fancy-pants international community picnic didn’t happen last summer, but it’s back. Conceived in France 30ish years ago, Diner en Blanc is a chic mass picnic, meant to celebrate public spaces, where you dress in all white, bring your own food and are ushered to a mystery location to eat with hundreds of other Haligonians. Register for your spot online.—Allison Saunders