How were these domes built?  I commented on "The Four Books of Architecture" and said that the domes just leave me in awe.  They are truly a staple in architecture.  I know nothing about architecture unfortunately, that's why I asked how domes like this were built.  I can understand how things are built today but I guess I must totally underestimate the people of this time.  Agreed, this should definitely be preserved!  It has a significant religious meaning as well as architectural, and its a gorgeous piece of art.