This was near a meadow once used for a CCC (Civilian Conservation Corps) camp.
We were intrigued by this jail-like structure when we came upon it. (Dad is
clowning a bit, here.) We later learned that the CCC men raised a pet bear cub
and when it became troublesome in their bunkhouse (chewing too many pairs of boots)
it was moved into this "den" on the nearby hillside.