On May 27, 1937, two hundred thousand excited citizens turned the grand opening of the iconic Golden Gate Bridge into a massive outdoor celebration during its car-free pedestrian day. Participants pushed strollers, roller-skated, and even tap-danced across the span to celebrate this engineering marvel, which opened to vehicular traffic the following day. The event proved so popular that the massive weight of the crowd actually caused the center span of the suspension bridge to flatten slightly, a testament to the immense engineering flexibility designed into the massive suspension cables.