"Old ideas can sometimes use new buildings. New ideas must use old buildings."That's because rent is cheap in old, run-down buildings, allowing aspiring entrepreneurs to try out ideas without costly overhead. Cities with old buildings in abundance have opportunities for economic growth that other cities can't match--no matter how much money they spend on new development. As Jacobs explains:
"The economic value of new buildings is replaceable in cities. It is replaceable by the spending of more construction money. But the economic value of old buildings is irreplaceable at will. It is created by time."