> ...are basically just .. really old housing.

Indeed, old is not enough. Old and grandiose (at least for that epoch) is what attracts curiosity.

For example, something like Stonehenge could be assembled in a matter of minutes with modern machinery, but several centuries ago it was more than the state of the art. Furthermore, it hints to a knowledge of astronomy which is daily knowledge in the epoch of Hubble, but is astonishing considerind that the first telescope would have to wait for Galileo to be born.

Another example: in Italy there are plenty of majestic cathedrals. We may discuss about the utility of spending so much money and man-centuries on cathedrals, but they are just so beautiful that you get speechless once inside.