Who were the instigators of the plot to build the Tower?
Rashi: "One man said to the other" refers not to individuals, but nation to nation. 1 Specifically involved were the sons of Cham
Gur Aryeh: Why does Rashi deviate from the literal interpretation? Later on (11:7), HaSh-m decrees, "that a man shall not understand the language of his fellow." In that verse, we cannot interpret that every individual person was given his own language, because there are only 70 languages. Therefore, the word "man" must mean "nation," and it means this here as well.
Why did the builders of the tower make bricks, rather than build with rocks?
Rashi: Because, since Bavel was situated in a valley, there were no rocks.
רש"י: איש אל רעהו- אומה לאומה: אולי הכונה 'איש לאיש' כפשוטו?
גור אריה: בפסוק ז' כתוב "אשר לא ישמעו איש שפת רעהו", ושם בודאי הכוונה לאומה שהרי התחלקו רק לשבעים לשון.