Don't forget the inner domes in Orthodox churches and the
   iconography-as-windows/doors. We humans have been doing
   immersion for a long time. Of course the ancients knew it wasn't
   realistic - wasn't supposed to be. The other-worldliness was
   their sci-fi of the day as it were. Between mood-altering
   frankincense, the chanting, the architecture - all a virtual
   reality environment using the available tech of the day. [the
   byzantines even used machinery sometimes - the stuff from Hero's
   workshop didn't go away but kept being used by the high courts -
   part of the Greek magic, while Rome and the poor Europe was
   going their their hordes and such.