From the nearby earthcache we learned that this cap is on top of a kame--a leftover from a glacier--and is one of the highest points in the city. People have been using this hilltop for 5,000 years to survey their surroundings so it's no surprise that a survey marker ended up here!
ManjaLou and ourselves enjoyed this little park and its views near and far. An osprey was an unexpected delight as it lifted off from one of the trees and soared and chirped overhead during our visit. The cap was quickly located, but what a sad thing it is to see. Careful examination will reveal a few letters around the edge but the center has been battered beyond recognition. Clearly another case for the SPCBC (Society for the Prevention of Cruelty to Brass Caps). Thanks for the cap and views.