On Tue, Jul 10, 2012 at 11:26 PM, Deryck Chan <deryckchan@gmail.com> wrote:

In general, other than flying and buying alcohol etc, no one is requires to carry ID in Europe.

However, advance warning: in Hong Kong, carrying photo-ID with you is mandatory by law for all persons aged 11 or over at all times in public places.

Deryck

The same is true in the U.S., but entering federal buildings in Washington D.C. constitutes an exception to the rule.