The main lobby of the Harris Theater for Music and Dance lies two floors below Randolph Street, its entryway sunk in perpetual gloom. Just to the east is an exit from the Millennium Park parking lot, but no arrows instruct drivers where to go. Turn right and at the L-shaped intersection you'll see a sign marking the ramp up onto northbound Columbus Drive. But if you want to avoid traffic, or have something to hide, you can opt for the eerily unmarked subterranean route alongside it to the left. It's a dank cement maze complete with rats but otherwise deserted, with any number of desolate spots suitable for doing the deed. Once done, you can make your escape by turning left into the further bowels of Lower Lower Wacker, a realm formerly of homeless people, now of shades. Or turn right and you'll break out onto the bridge beneath the Michigan Avenue bridge, winding up in a netherworld by the NBC tower, incongruously close to the lights of the Magnificent Mile, yet unseen.