For me appreciation is much more important than understanding. I read an interesting article about how society as most of us know it is predominately right-brained ie. analytical, rational calculating. In a very deep way we have discarded the left brained part of humanity as part of daily life which is probably why artists and art has polar reactions of profound appreciation or profound bafflement. We are a bit disconnected from that part of ourselves and when we see it in action we either cant 'get our heads around it' or else have an amazing irrational feeling of connection to it.

Getting to the point, its likely the societies that built these monumets were much more holistic in their approach to life, the irrational was as much a part as the rational so these monuments dont 'fit' into the modern way of thinking about the world and probably never will. Its like trying to catch fish with the rod but no line. On the other hand we have the other side of the coin where the predominately left-brained people of the world approach the problem with their own way of understanding, creativity and 'wholeness' where everything is connected and the gaps are filled by the imagination. I think ancient man had a certain blend of both parts of the brains function which is extremely rare in 2006 which is why we have polar approaches from the mystic an esoteric to the hard-edge of the analytical.