David Cittadino submitted the route:

A loop from Adirondack Loj to the summits of Mt Gray, Skylight and Marcy.  About 18 miles.

Forward or reverse loop.  

See GPS tracking in the various FKT attempts for detailed directions.
 

An Indiana Dept. of Natural Resources 'challenge' to complete all 6 ravines of the Shades State Park. The lap is a linkup of most of the park's trails and the route is listed on a sign in the Hickory Parking lot.
https://www.in.gov/dnr/parklake/files/sp-6RavineChallengeBrochure.pdf

The route is an out & back of the paved paths of the North Branch Trail system, reaching from northern end of Chicago to the botanic gardens in Skokie. Out & back on the Red trail, and complete loop of the Black trail (36.4 miles total) on this map:

https://map.fpdcc.com/#/?trail=North+Branch+Trail+System

VARIATION:  There is now a Variation which is the same trail one way from Chicago to Northbrook: