Wellington, New Zealand
Wellington, with an urban population of less than 200,000 (and 500,000 in its metro areas), is not as large as the other places on this list. However, art galleries, wine bars, a great nightlife and cosmopolitan vibe make this city feel much larger than it is, and has earned it comparisons to places like Hong Kong and San Francisco.
The relatively small population and geographic isolation lend the New Zealand capital naturally fresher, cleaner air, which works well with its pedestrian-friendly center. Pair that with a kind of small-town attitude and appreciation for nature, and it's easy to understand how keeping the streets clean is part of the local culture.