^It's still the single largest privately owned office building in the world and the 2nd largest overall after the Pentagon. The skydeck pavillon is home is the biggest f'ing pile of Legos I've ever seen, the plaque said it contained 50,000 bricks and is 20 feet tall.
I went into the main lobby, which is open to the public (at least as long as you're going to be shelling out money to one of the restaurants spread out on the 2nd floor and 1st basement). I have no idea if photography is allowed, but that didn't stop me. As far as they knew I was a guy with a tasteful shirt and tie checking email on my phone. Those concerned about security should rest easy knowing access to the elevators is locked the hell down.
Stairs from Wacker Dr atrium down into main lobby.
Franklin St. half of the lobby. 1st floor has a few stores and a corner bakery. 2nd floor houses more restaurants. 3rd floor has offices and some kind of conference center. The 3rd is all leased, private, secured offices, so no going up there for a look.
Franklin St. entrance.
There's only two 3-story high openings, in the west and east central tubes. Right now there's some really crappy modern art on display (out of frame) in the southern half of the lobby.