The internal rooms could be converted into a grand habitable space.

It's also large, with about 300 sq metres of habitable space.

However, very few cellars have the requisite head height for a habitable space (7ft, or just under 2.2m) and if you have to dig down or underpin, prices skyrocket.

In more recent science fiction, humans may create habitable space (by terraforming or constructing a space habitat) and call that a colony.

Fit-out (tenant work): the physical products and spaces controlled by the individual inhabitant or occupant used to make habitable space in a base building.