PARIS, July 27 — French President Emmanuel Macron declared the Olympic Games open on Friday after a soaking wet ceremony in which athletes were cheered by the crowd along the Seine, dancers took to the roofs of Paris and Lady Gaga sang a French cabaret song.

France’s three-time Olympic gold medallists Marie-Jose Perec and Teddy Riner then lit the Olympic cauldron, suspended on a hot-air balloon, before Canada’s Celine Dion sang Edith Piaf’s Hymn to Love, in her first public performance in years, drawing huge cheers from the crowd.