This branch of the Smithsonian Institution displays its collection around the grand rotunda of the 1907 Custom House located at the bottom of Broadway (which, many moons ago, began as an Indigenous trail). The life and culture of Indigenous Americans is presented in rotating exhibitions—from Navajo jewelry to ritual tribal-dance costumes—along with contemporary artwork.
The museum is a branch of the NMAI in Washington D.C. and thus officially an extension of the Smithsonian Institute—which is why it’s free (well, not entirely; your taxes pay for it). No tickets are required, just show up to explore.