How did the Human population rebound so fast after the great flood?

Genealogies in Genesis put the Tower of Babel about 110 to 150 years after the Flood. How did the world population regrow so fast to make its construction (and the city around it) possible? Similarly, there would have been very few people around to build Stonehenge and the Pyramids, rebuild the Sumerian and Indus Valley civilizations, populate the Americas, etc. Even if these people reproduced at ever possible time, there would NOT be enough people to build all these things when they were built.