Source: Arturo Holmes/MG23 / Getty The Met Gala returns this Monday, May 4, which means the stairs at the Metropolitan Museum of Art are about to turn into the most-watched runway in the world again. Officially, the Met Gala is the Costume Institute Benefit, an annual fundraiser held on the first Monday in May and opens the Costume Institute's spring exhibition. The event started back in 1948 as a much smaller fundraiser. Still, over the years, it has grown into fashion's biggest night, where celebrities, designers, musicians, actors, and athletes pull up, trying to make a moment.