This is an apples to oranges comparison. Roman civilization lasted a good deal longer than the Roman Empire: ~2,200 years of civilization (753 B.C. to A.D. 145

This is an apples to oranges comparison. Roman civilization lasted a good deal longer than the Roman Empire: ~2,200 years of civilization (753 B.C. to A.D. 1453) versus ~500 years of Empire (27 B.C. to A.D. 476). And that's if you don't count, as other commenters have, the Roman institutions (including the Catholic Church) surviving the Western Empire's political collapse as the continuation of a broader Western civilization.