San Francisco's population density is 1,400 people per square kilometer. There are many beautiful, beloved cities throughout the world that manage to accommodate far greater density numbers
So neat to see Barcelona on this list having just returned from spending a few days there in January. As I was walking through the streets there I was thinking to myself, "Wow, wouldn't it be amazing if San Francisco could have multi-story apartment buildings block after block like this. This feels like a real city!"