THE SLIP
The Ogden Slip - the location of the Hellgate.
Just north of the Chicago River sits the slip that allows boats to dock from either the river or from Lake Michigan through the Chicago Harbor. However, that's not the most valuable piece of the puzzle for The Watchers in this area. No, it's what's on the stretch of land between the river and the slip that matters.
On that land is what appears to be a drainage well - that is the Hellgate. The well is a perfect circle carved into the land, and it sits at exactly one hundred feet wide. If you drop an Obol into the well, the Hellgate will open allowing either you, or whomever you're calling forth, to cross between worlds without problems.
The peninsula that has the Chicago River, the Ogden Slip and Chicago Harbor against is very easy
