Museum Day Live! is an annual celebration of boundless curiosity hosted by Smithsonian magazine. Participating museums and cultural institutions across the country provide entry to anyone presenting a Museum Day Live! ticket. The Museum Day Live! ticket provides free admission for two people on Saturday, September 23rd. The Museum is open from 1-5pm.
Details and tickets here: http://www.smithsonianmag.com/museumday/museum-day-live-2017/