sentences:  Together, they enter the outskirts of Knoxville, where I-75 overlaps itself with a different road, this time I-640, but only for a short time.When the two meet I-275, I-75 encounters some of its highest points of elevation through the Cumberland Mountains and Cumberland Plateau region, cutting through the uppermost peaks and ridges of the mountains.I-75 continues northbound through the hilly, rugged terrain of the Cumberland Plateau region of Kentucky passing through London and Richmond, eventually reaching Lexington, where it briefly runs concurrently with I-64 before splitting off in the direction of Georgetown.