Catoctin Mountain Range ... Catoctin Mountain Park (NPS) ...
There are a pair of adirondack shelters like this one in the north end of the park off a horse trail that intersects with the Catoctin Trail. If you're interested, you will need to make a reservation. I recommend against visiting in the summer, as the area around the shelters is swampish. Additionally, I found the shelters to be dirty inside, and there are no brooms in the shelters of the sort that you would expect to find in shelters on the Appalachian Trail, so you might want to bring your own. On the other hand, one of the shelters features a tie-up for your horse This could be an ideal overnight for horse riders.
Each of the two shelters features a camp site in front, including stumps to sit on and a fire ring with grill for camp site cooking. Here, this stump has hiking equipment set out on it, including a map for planning a hike. The hiking in the area is nice and varied.