It's true that because of the Great Fire of London, much of the city dates no farther back than the 1670's, a period of time when America already existed, albeit as a series of colonies. But a walk through the Tower of London (which survived the devastation) reminded me how much more recorded history they have. And the Museum of London (in the City of London) had artifacts from Roman times. There's even a stretch of Roman-built wall outside the museum (uncovered during the Blitz, if you're a silver lining kind of person).
But what's really cool about London is the old and new are all cheek-by-jowl, just like the modern office building looming over the Roman wall in the photo above. The double-decker bus would round a corner and there would be some elaborate Victorian monument surrounded by glass and steel towers, sometimes in odd shapes. There was one stubby glass tower that I thought looked like a cartoon rocket ship but London cabbies have dubbed it "the gherkin." It made a great backdrop for the Tower.
I'd go back in a heartbeat.