After the flood, the descendants of Noah were journeying out and being “divided on the earth” (Gen. 10:32; 11:2). “And it came to pass…they found a plain in the land of Shinar, and they dwelt there” (Gen. 11:2). The fact that they stopped journeying and “dwelt there” is significant. There they said to one another, “Come, let us” (notice the pronoun “us”) “build 
ourselves” (“we” will do it and do so for “us”) “a city, and a tower whose top is in the heavens” (may simply speak of great height, cf. Deut. 1:28; 9:1), “let us make a name for ourselves” (again, it’s all about them). Now, here’s the kicker in the last part of the verse; look at their motivation: “LEST we be scattered abroad over the face of the whole earth” (Gen. 11:4).
Why does that matter? Because God had plainly commanded, “Be fruitful and multiply, and fill the earth…Bring forth abundantly in the earth and multiply in it” (Gen. 9:1, 7). By stopping in Shinar, by dwelling in Shinar, by building a city in which to dwell, God’s people were, in effect, saying, “We don’t want to ‘go into all the world and fill it,’ so LEST that happen (and we do what God says), let’s stop here!” Outright disobedience to the will of God — NOT a great idea!