shambles -if ET's wiuth no concept of religion etc.etc. they would probably conclude it was used as a marketplace and teaching center - which most cathedrals were - sometimes even WHILE services were being held.

Once a building is in place - it can and will be used for many purposes. However a more logical approach would probably conclude that the scale and care taken in the detail and twiddly-bits of a cathedral would make it very different to what was usually required for a teaching centre and marketplace.

Perhaps our approach to grand buildings has changed along with the time-scales required in their construction. The biggest projects now only take a few years. Stonehenge for example was in construction for many hundreds of years. Perhaps it was less the end result - but the process and what was involved in it?