San Francisco's Victorian-era row houses are models of efficiency. With more than a dozen crammed onto a single block, they take up little of the landscape while maximizing living space by rising vertically. Row houses' shared side walls reduce both the amount of building materials used and the places where heated or cooled air can leak out; only the front and back walls are exposed to the elements. Framed and sheathed in rot- and insect-resistant redwood harvested from local forests, they hold up well in the foggy city. Instead of shady porches, San Francisco row houses have projecting bay windows that capture sunlight and brighten interiors. While some Queen Anne examples have pitched roofs, most have flat roofs for this snow-free zone. Their high ceilings and double-hung windows promote air circulation. And they are easily adapted for reuse; many have been transformed into apartments.