'bug is on the trail!
i guess i could hold out for a more detailed answer, but the appalachian trail will do.
the top picture is an alpine shelter, or lean-to that i spent many winter nights on solo backpacking trips. the side you can't see is open to the elements, but there are 2 small fireplaces for the really cold nights. if the world ever goes to heck in a hadbasket, that's where you'll find me. i've even rebuilt parts of it after some rotten people chopped and burned sections.
the second is a feature on the trail called the lemon squeezer. it is a fracture in a huge rockface that the appalachian trail goes right thru. it's difficult to maneuver with a day pack on your back, let alone a thru hikers pack. but if you don't go thru, you haven't completed the trail.
ok 'bug, you're up.