|Massive circular doors could be
rolled into place by three men.
These doors were placed in
narrow hallways. Once the
enemy was near the door, they
could shoot an arrow through
the hole to defend themselves.
|Fresh flowing water, ventilation shafts, living
quarters, schools, shops, tombs, and escape
routes. They even had sophisticated
communication shafts, allowing people
to whisper from one floor to another.
|People lived in these
underground cities for
weeks at a time.