The people of Nimrod's time knew the story of the mabul (the flood). They were constantly afraid it would happen again. That is why they settled in the valley of Bavel. Together they felt strong — against nature, but also against Hashem.

Six hundred thousand people helped build the tower. The plan for the city they forgot. Four men resisted the building of the tower: Noach, his son Shem, his great-grandson Ever, and Avraham. "Against whom are you trying to fight?" Avraham was 48 years old then. He walked along the building pit and said to the builders: "You are forgetting G-d, who is the true Tower. Instead you take a tower of stone." The people did not listen to him. They said: "Look at this barren mule. He cannot have children!" Nobody minded the protests. On every brick they wrote their name. G-d did not stop them — not yet.

Remember chapter 1 — man was given his place: to work the earth and to guard it. Here, people try to take the place of Hashem.