Street Lab ~ The Uni Project is a nonprofit that provides programming in parks, plazas, and other public spaces all around New York City. You might remember seeing them at The Plaza ~ Uptown Grand Central in East Harlem.
The Uni Project has created pop-up installations over 500 times in about 150 locations. Here is a map showing where they pop-up around the City in 2017. Looking forward to seeing them again this year.