One of the cool things they do in Dark Souls is use the skybox - or what would normally be the skybox, I’m not sure of the technique they’re using - to show the topology of the area. Many important locations in the game can be seen in the background, even if it’s not obvious you’ll get to visit there at first.
My favorite use of this (that doesn’t involve boss fight foreshadowing) is the giant tree above the Firelink Shrine. To the best of my knowledge it’s not a place you can visit, but it adds a ton of atmosphere to the area. It’s almost certainly drawn from an image and not geometry, but Dark Soul’s use of a depth-of-field camera to add progressively stronger blur to things based on their distance from the player makes it tricky to tell sometimes. It could be a blurred image, but parts of it could easily be blurred geometry. Slap on some bloom and some god-rays and it seamlessly blends in to actual distant level geometry.
Dark Souls (2011)