Hall of Infinite Doors

"Sorry, chap. The gate's locked, and I lost my key. I'm not allowed to move away from my post, so I can't look for my key." Saint Peter says. You find it to be fairly ridiculous that somebody could lock the gate to heaven and lose his key while standing in one place. "Maybe you could find it for me?"
"Of course!" you reply.
"Thanks, lad. Whatever you do, do NOT look under the urn.