Every first Monday in May, the most influential personalities of pop culture are invited to climb the red carpet steps of the annual Costume Institute Gala of the Metropolitan Museum of Art in New York. Nicknamed Met Gala or Met Ball, the event celebrates a special theme every year, ushering in the museum's new fashion show. The opportunity for designers and their muses to collaborate to create an unforgettable look on the theme of the event. So many guests enjoy this exceptional dress code as a unique opportunity to create a historic look. From the endless dresses to the most scandalous outfits, zoom in on the 20 looks that have forever marked the history of the Met Gala.