Either watch the building of the Tomb of Tutankhamun. Watch and record what happens. I can't interact or interfere (which mean I would have zero effect on the time line), but I would have video evidence of how they did it. Since it took years to build (supposedly) we don't really know how long it took, I would watch the beginning week or two of it.

Be a hell of a shock if it really was "aliens". lol