Three volcanoes buried this plateau in ash. The ash set into tuff — soft enough to cut with a hand tool, firm enough to hold a ceiling. Where a harder cap survived, the rock beneath it was spared while everything around it eroded away. That is a fairy chimney, and there are thousands.
People saw early what the stone allowed. A room could be dug in weeks, stayed cool in summer and warm in winter, and cost nothing but labour. So they dug — houses, stables, cellars, churches with painted ceilings, and whole towns that went down instead of up, deep enough to hide a population for as long as a siege lasted.
Almost none of it was built to be looked at. Every hollow here began as something somebody needed.