The Quay, Exeter. In the pic above, we can see three distinct historical land uses and about 200 years worth of buildings. On the left, a covered commercial market, in the middle are vertical warehouses, and residential on the bluff above. Granted the houses appear to be upper end, and they are separated from the action on the harbor, but imagine these kinds of houses anywhere near commercial and industrial uses in today’s world.
Note too the reuse of the buildings. The warehouses are now offices, galleries, cafes and shops. The commercial market still functions. And the houses are still desirable. Mixing land uses and building to last are great low energy strategy for cities.