With the world explored and mapped, it is hard to fathom new cities being built. Nevertheless, that will certainly happen in the future.

What will the catalyst be? Will it be nuclear war, which devastates and contaminates an area for decades? Will it be disease that makes existing urban areas less desirable to live in? Will it be economic opportunity, as we discover new uses for land or a new way to use land? Space Travel?

I see a small parallel to startups: it is easy but dangerous to say "there are no new ideas in that industry". Yet often some of the primary companies are those that survived the early "land grab" of customers.