Alberobello is in fact an example of a medieval tax dodge. The king of Naples set a tithe to be payed for new settlements, so the local nobleman Gian Girolamo required his tenants to use a dry stone wall technique without mortar. These houses were classified as temporary shelters and therefore the payment could be avoided. The resulting clusters of circular cone topped trulli are super cute. There is even a trullo sovrano with two stories built for a local priest. Many have now been converted into shops, restaurants and B&B's.
In the center of town there is a small trullo bar called the Belvedere from the terrace you can take excellent photos of the roofs of the trulli, however while you are there pop in for a coffee and a chat with the owner.