A hilllside environment I created the other day. The mist was an interesting challenge using volumetrics and half transparent cloud textures on planes.
The entire "valley" was created in World Machine and then I used Blenders microdisplacement feature to get the geometry into the scene.
Photoscanned rock assets from Quixel Megascans and textures from Poliigon.com, with some exceptions to Cycles Material Vault
To the question of whats holding the house up:
Very strong beams I reckon. I dont know that's up to the construction engineer to figure out :)