Underappreciated benefit of free D.C. museums: free museum bathrooms. And leave it to a museum dedicated to the study of architecture to get their johns just right. A mix of shiny metal and frosted glass means you can relieve yourself in retro-cool style. The museum spared no expense to get the details just right. The bathrooms are spacious, always clean, and almost always empty. Fringe benefit: You get to walk through the Great Hall and you won’t get hassled by the security guards. You can do your business in peace.