The Flatiron Building, formerly the Fuller Building, is a few blocks away from Volumes bookcafe, where Brendan Detzner holds Bad Grammar Theater every month. Filled with art studios, a hair salon with the ominous and cool name I'll Cut You, and years ago the wonderful House of Monsters, this place still has a hand crank elevator.
And the interior is painted with clowns. I've tried to find out more information about the artist, but have come up with nothing. Hopefully someone will see this post through the Google machine and will contact me.