[delinka]

Pyramids also come to mind.

[driax]

The pyramids were not built by slaves (at least there's no real proof of it). A lot of the workers who died during the construction where buried in decorated tombs which says something about their wealth, which probably says they couldn't be slaves.

[dmm]

off-season farmers. During the yearly Nile floods the fields would be covered.

[onurozkan]

ALIENS!