A tangential internet search perusing quarries in the NY/NJ area led me to the www.nynjtc.org/ site where you can search for hikes by category like "quarry" or "cemetery" or "ruins." Very cool. This hike through Granite Knolls park up near Yorktown, NY is the site of a former quarry and farm with glacial erratics--huge strangely shaped boulders left behind by glacial ice--scattered across the park. You can find farm equipment, small pit quarries, and these massive sharp edged boulders a couple miles in from various trailheads.
Granite Knolls itself doesn't have it's own parking and trailhead, but we hiked in via the Yorktown Trailway--a wide path that parallels the Taconic State Parkway. We got a late start to the hike but decided to bring headlamps just in case we got caught in the dark. Well, we did. And right before dark we decided to book it straight down the mountain in an eastern direction towards the car instead of trying to follow the multiple different trails and intersections you have to pay attention to in the daylight to reach the Giant Boulder. Turns out this is a pretty fantastic way of getting from point A to point B in these woods--trees are sparse and thin and the trails are covered in leaves anyway, leaving you to keep a keen eye out for 5 different colors of blazes.