The point of cities is multiplicity of choice.

New ideas often need old buildings.

...frequent streets and short blocks are valuable because of the fabric of intricate cross-use that they permit among the users of a city neighbouhood.

observation of realities has never, to put it mildly, been one of the strengths of economic development theory.

To approach a city, or even a city neighborhood, as if it were a larger architectural problem, capable of being given order by converting it into a disciplined work of art, is to make the mistake of attempting to substitute art for life. The results of such profound confusion between art and life are neither life nor art. They are taxidermy.

(The psuedoscience of planning seems almost neurotic in its determination to imitate empiric failure and ignore empiric success.)

Cities need old buildings so badly it is probably impossible for vigorous streets and districts to grow without them.... for really new ideas of any kind--no matter how ultimately profitable or otherwise successful some of them might prove to be--there is no leeway for such chancy trial, error and experimentation in the high-overhead economy of new construction. Old ideas can sometimes use new buildings. New ideas must use old buildings.