DURING THE NBA playoffs in 1967, there was a scalper who stood outside of Convention Hall. He would approach you and quietly ask whether you wanted to get inside; 10 bucks a head, twice the regular ticket price. He would tell you to follow him down the dark alley on the Hall's south side, where he would stomp on a manhole cover that would magically pop open. He'd shimmy down a ladder and guide you through a maze of pipes and machinery, under the building to the other side, then up another ladder and out another manhole cover.
He would approach an unmarked door, knock in code - thump-thump-a-thump-thump, - and the door would open, in you go.