Located in Black Hill Regional Park, Germantown, Maryland (about 30 minutes NW of Washington DC, and 5 minutes off of Route 270), roughly at 39.204494, -77.287382 in GPS coordinates.  Starting at the Cabin Branch trailhead on the main park road (close to the park entrance, but no official parking at the trailhead), hike in less than 1/4 mile until you cross a slight ridge in the trail, with several large white quartz rocks in the trail bed.  Locate the three quartz rocks (naturally) aligned in a row across the trail, and look southerly into the woods along that direction.  The pyramid is on a slight rise about 100 feet into the trees.  The closest parking lot is about a mile from the site.  A park map is shown below.