From the Milwaukee county Parks site:
"In the early 1900s, Frederick C. Wulff, the first Superintendent of Horticulture for the park system, developed paths which served as the foundation of the Seven Bridges Trail. He lived with his family in what is now the park's overnight lodge, grew nursery stock in the Wil-O-Way area, planted many of the non-native trees found in the park, and raised pheasants and geese here.
In the '30s, the trail was further developed as a Works Progress Administration project. It required a crew of over 200 Civilian Conservation Corps workers to construct retaining walls along creek beds and throughout the ravine, and to create lannon stone paths and staircases.
Over the years the trail system declined, but in 1995–96, five young members of the Wisconsin Conservation Corps, trained by Park Maintenance staff, reconstructed damaged sections of the trail, rebuilt staircases and six bridges, added railings and signs, and remodeled the overnight lodge. The covered bridge was renovated by Parks Maintenance staff."
The part of the trail where the cache is is actually the original WPA's work. The WPA was one of the most enduring artifacts of FDR's New Deal, and among the many great things it accomplished was building this wonderful resource here in Grant Park. Over 200 area people were employed to build the Seven Bridges trail, laying down tons of lannon stone to create the steps, trails, and retaining walls that we enjoy over 70 years later.
Please re-hide the same way you found it, to keep muggles away and to comply with the hint. Oh, and really, avoid the hint unless you really need it.
FTF will get another history lesson with the travel bug I popped in here to start things off.
Permission to place granted by Milwaukee County Parks Manager Brian Russert, Permit #386.