Michigan is a fairly large state,
you may be best to look for caverns and craters, variables in elevations, so to find mountainous regions, or low lying areas with ponds and creeks,
as for buildings, that may be rare or time era related, look for oldest pioneer locations, and some abandoned mines or factories, also seasons have impact, winter(whites), late spring (greens), and fall (oranges), if you've time to travel from south to north points, then you will find lots of hidden treasures along the way, many old villas and historic sites,
Trail Tree on "Mount Arvon"
Detroit Shipbuilding Company , Wyandotte, Michigan.
Mackinaw City, Michigan.
Ypsilanti, Michigan, Starkweather Chapel,
Whitefish Dunes Cave Point County Park
Michigan National Forest