I believe I read somewhere that it's a requirement for tourists in Germany (or maybe everyone?) to carry some sort of ID with them at all times. Would my US drivers license be sufficient, or do I have to carry my passport? If it's the latter, that seems to contradict most advice I hear that says to leave the passport locked up in a hotel safe.

And would anyone happen to know if the UK has the same requirements? I didn't want to start 2 threads on this if I didn't have to.

Thanks