Housed in a distinctive Romanesque Revival building (a former public school), P.S.1 mounts cutting-edge shows and hosts an acclaimed international studio program. Artwork crops up in every corner, from the stairwells to the roof. P.S.1 became an affiliate of MoMA in 1999, and sometimes stages collaborative exhibitions. Reflecting the museum’s global outlook, it has focused in recent years on such luminaries as Janet Cardiff and Olafur Eliasson. It also hosts summer’s popular Saturday-afternoon party, Warm Up.