Docklands in London and La Defense in Paris. Cities have a mix of residential areas, generally good and bad areas very close to each other. Apartments and multi-purpose buildings predominate. Public housing is evenly dispersed throughout the cities. Partly a natural consequence of age of cities - built before cars were common so streets are narrow and parking is very limited.
Limited parking is expensive - pollution and congestion are huge problems.
Most of the largest cities in the world are now in the Third World and the most rapid urbanization is taking place there. Architecture reflects colonial power. Today often retained as the capital city of independent countries. Entrepreneurs - You have to have a group of entrepreneurs or risk takers who can marry the capital to the innovation. Impetus - finally you require some kind of impetus or crisis to overcome the inertia of the existing economic system.