Gotta be Berlin like altamiro says is one of the greenest cities in world - especially old West Berlin with miles of forests within its limits.

Of course the concept of 'city limits' throws everything off. Berlin is huge, as is London, due to both countries having a different way of organizing municipalities.

Europe has 75,000 municipalities and 36,000 of them are in France. The largest city in France is Arles. Marseille is 4th in size, Fontainebleau is 21st, and Paris is.... 113th.

Excuse me -- instead of Europe, I should have said "EU-15".