Underground cities, underground homes associated with above ground homes, bunkers, shelters, even cultures within cities, have been with us for millennia. But as regards millennia, our is the only civilization where an actual apocalypse, whether natural or human made, has been reason enough for building substantial underground residences. Now a company named Oppidum, has taken it multiple steps beyond – in the creation of multi-million-dollar underground luxury sanctuaries, costing, generally between $40M to $100M and over.
