House symbolism is an interesting way of looking at a story. Most stories have a home in there somewhere.
Some (e.g. Scherner) interpret houses in dreams as stand-ins for the human body. The windows, doors and entrances are the entrances into the body cavities. The facades are smooth or provided with balconies and projections to which to hold. In anatomy the body openings are sometimes called the body-portals.
Dwellings in fantasy don’t always look like the rectangular structure we know and love.
Bilbo’s circular house feels particularly cosy, in stark contrast to the jagged mountains in the distance.