The cache is NOT hidden at the given coordinates (so don't go the middle of a busy intersection). In order to find the true location of the cache, you will need to complete the "Historical Markers of Ann Arbor, Michigan" Adventure Lab. The cache is hidden at: N 42° AB.CDE W 083° FG.HIJ. Completing each lab cache will give you a part of the true coordinates, and therefore completing the entire Adventure Lab will give you the full coordinates. While completing the Adventure Lab and getting the true coordinates may not be difficult, finding this bonus cache might be a little trickier due to potential times of high muggle traffic and activity. Please replace back as you found it, which should be its intended hiding spot.