Known as the "city of the Trulli", Alberobello was named a World Heritage Site by UNESCO in 1996. It is an exceptional example of construction using prehistoric techniques and numerous trulli have survived intact and are still functional to this day. A "Trullo" is a small limestone house with a typical conical roof, made with dry stone walls made with limestone boulders collected from the nearby fields. Alberobello boasts the highest number of Trulli, but they are typical of the whole of the Itria Valley and you can find them in Locorotondo, Martina Franca, Cisternino and Fasano.