If you haven’t made your way down to Gallery Place today, you’re missing quite the celebration. The Smithsonian American Art Museum and the National Portrait Gallery opened their doors today after a six year renovation. Dancers, puppet-masters, Andy Warhol impersonators and live bands are ushering in the new era for the former Patent Office Building. Oh, and the free ice cream is nice, too. After the ribbon cutting ceremony this morning, residents and tourists…