A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
gen 11:1CONFUSION OF TONGUES. (Gen. 11:1-32)
the whole earth was of one language. The descendants of Noah, united by the strong bond of a common language, had not separated, and notwithstanding the divine command to replenish the earth, were unwilling to separate. The more pious and well-disposed would of course obey the divine will; but a numerous body, seemingly the aggressive horde mentioned (Gen 10:10), determined to please themselves by occupying the fairest region they came to.
gen 11:2land of Shinar--The fertile valley watered by the Euphrates and Tigris was chosen as the center of their union and the seat of their power.
gen 11:3brick--There being no stone in that quarter, brick is, and was, the only material used for building, as appears in the mass of ruins which at the Birs Nimroud may have been the very town formed by those ancient rebels. Some of these are sun-dried--others burnt in the kiln and of different colors.
slime--bitumen, a mineral pitch, which, when hardened, forms a strong cement, commonly used in Assyria to this day, and forming the mortar found on the burnt brick remains of antiquity.
gen 11:4a tower whose top may reach unto heaven--a common figurative expression for great height (Deu 1:28; 9:1-6).
lest we be scattered--To build a city and a town was no crime; but to do this to defeat the counsels of heaven by attempting to prevent emigration was foolish, wicked, and justly offensive to God.
gen 11:6and now nothing will be restrained from them--an apparent admission that the design was practicable, and would have been executed but for the divine interposition.
gen 11:7confound their language--literally, "their lip"; it was a failure in utterance, occasioning a difference in dialect which was intelligible only to those of the same tribe. Thus easily by God their purpose was defeated, and they were compelled to the dispersion they had combined to prevent. It is only from the Scriptures we learn the true origin of the different nations and languages of the world. By one miracle of tongues men were dispersed and gradually fell from true religion. By another, national barriers were broken down--that all men might be brought back to the family of God.
gen 11:28Ur--now Orfa; that is, "light," or "fire." Its name probably derived from its being devoted to the rites of fire-worship. Terah and his family were equally infected with that idolatry as the rest of the inhabitants (Jos 24:15).
gen 11:31Sarai his daughter-in-law--the same as Iscah [Gen 11:29], granddaughter of Terah, probably by a second wife, and by early usages considered marriageable to her uncle, Abraham.
they came unto Haran--two days' journey south-southeast from Ur, on the direct road to the ford of the Euphrates at Rakka, the nearest and most convenient route to Palestine.