Lava Buildings

I am myself unsure as to how well this would work.

Currently, rock is quarried, modified, shaped and transported distances to be made into buildings in the form of bricks, concrete, mortar and sometimes actual stone such as granite or marble. This renders it vulnerable to damage. Instead, moulds made from some kind of refactory material such as tantalum carbide could be assembled on-site and filled with molten rock in order to form solid buildings of specific rocks, including window frames, ceilings, walls, floors, plumbing, cavity walls, conduits for wiring, doorways and so forth, in whatever shape desired. I have previously mentioned "limehouses", and I stick by that idea, but it occurs to me that less water-soluble compounds such as silica are amenable to this form of construction.

This is the bit I'm not sure about: I suspect big, monolithic buildings would be more vulnerable to damage by subsidence and other natural hazards than houses made of brick, but I'm not sure. If not, and they are in fact more durable, the prodigious energy use they embody would pay for itself with their relative immunity to damage and low maintenance needs.