Whoever laid the blocks of the monuments you mention was, unless you have evidence to the contrary, an ancestor of ours, one in a long, continual, unbroken line of life, and those who think they must have been some forgotten xcivilisation with amazing technical abilities, or who for some reason disappeared completely, always fail to provide the facts upon which ob jective evidence can be based. There are many unknown facts, but they are 'don't knows' not assignable to a race or group for which facts are missing.

Susan