A rock the size of the Empire State BLdg. could definitely take out a large city. At least no nuclear fallout.
This one is up to 1600ft in diameter — nearly a third of a mile — if it hit on land, it would end our civilization.
The Meteor Crater object was about 100 yards across (about one-fifth in three dimensions, or less than 1/125th the size of something 1500 ft in diameter) and dug a hole a quarter mile deep and over 3/4 mile wide, plus ignited everything flammable for probably dozens of miles, knocking down everything else.