An aerial view shows the famous cone-shaped, limestone-slab roofs of Alberobello, Italy.

The peculiar rooflines of these cottages, called trulli, help move rainwater to aquifers, and their extremely thick, stuccoed walls help keep the homes cool. Earlier trulli were built without stucco, supposedly to allow residents to dismantle them easily when tax collectors approached and avoid property taxes.

(Photo shot on assignment for, but not published in, "Down the Ancient Appian Way," June 1981, National Geographic magazine)