This is the Alamo, a sculpture in Lower Manhattan commonly known as the Astor Place Cube. (It's near Astor Place and Cooper Union.)
It was originally (in 1967) a temporary art installation created by artist Tony Rosenthal, who has a thing about cubes. But the people of the area liked it so much, they petitioned the city to keep it. And it's now just a happy element of this area of the city.
It's been played with any number of ways:
Redecorated by the visual artist Olek;
Covered to look like a cube from the video game "Portal";
And redone as the classic Rubik's Cube.