1. Mattress Factory
Where is it: Pittsburgh
What is it: Pittsburgh might be the hometown of pop art legend Andy Warhol, but the city’s Mattress Factory is where you will find today’s most cutting-edge modern art.
Why go: Come for the permanent Yayoi Kusama Infinity Dots Mirrored Room, but stay for the mind-bending Sarah Oppenheimer illusion and James Turrell's Pleiades, a work that can only be seen after sitting in a dark room for 20 minutes while your eyes adjust.