‘I should have seen the pattern before you did! After all, we have a precedent. The Weapons are technology gone wild, made things modified by time, grown into a kind of ecology – and so are the buildings of this “city”.’
Once, surely, the buildings had been intended to house people. But they were advanced technology: mobile, self-maintaining habitats. They fuelled themselves with light, and with organic traces – perhaps they had been designed to process their occupants’ waste.
Things changed. People abandoned the buildings, and forgot about them. But the buildings, self-maintaining, perhaps even self-aware in some rudimentary sense, sought a new way to live – and that new way diverged ever more greatly from the purposes their human inventors had imagined.
-Xeelee: Endurance, "The Lowland Expedition"