LargePepperoni

Just white squares.

party1981

The tile background is white squares. It could be anywhere.

pizzathrowaway

There is no "abandoned subway system" "under Comet Pizza" on Connecticut Ave.

There is an abandoned streetcar turnaround under Dupont Circle, which is on Connecticut Ave, but the tunnel ends 3.3 miles from Comet Ping Pong, as far as anyone can tell. http://wtop.com/wp-content/uploads/2015/01/DupontUnderground_Map.jpg

We know that Podesta owns artwork by that artist, but I haven't seen anything indicating that he owns any art with that tile background, have you?