There were generators aboard to power the turrets and searchlights, all the living and working spaces in the superstructure were duplicates of the real thing, and the Navy sent a complement of officers, sailors, and marines to wow visitors by miming the work of a functional warship crew.
With all the expense involved in creating the Potemkin village warship, it would have almost been easier for the Navy to just build a battleship for the visiting crowds to gawp at, and then sail it off to join the fleet after the expo. Two problems prevented that, however. First, there was as yet no way to get a ship that big to the ocean from Lake Michigan. Second, international treaties cause the Canadians to flip their shit when we put M240s on motorboats, so you can imagine what an actual battlewagon would do to harsh their mellow.
It was intended to relocate the Illinois up the beach a ways to Navy Pier after the Exposition, where it would have served as a headquarters building for the state's Naval Militia, but nothing ever came of it.
No Indiana-class pre-dreadnoughts remain afloat. In fact, steel warships of this period are super scarce; there's the Mikasa, once the pride of the Chrysanthemum Fleet, in Yokosuka, and her one-time foe, the Tsar's protected cruiser Aurora, in St. Petersburg. On this side of the pond there's the USS Olympia in Philadelphia (ever in peril, see it while you can) and the turret ironclad Huáscar down in Chile.
If you're a SCUBA-American, however, you can visit the remains of BB-2, USS Massachusetts, off the coast of Pensacola, where she was scuttled and her hull used as a target for coastal defense forts and railway guns.
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