Here’s a detail from one of the roofs of the trulli houses of Alberobello (see above). It’s a real art to stack the un-mortared slabs of stone to make a solid and long lasting roof. Even though the techniques are similar, because no two houses are the same no two roofs are the same. Each is a form of architectural sculpture. Here, in a notch created by the confluence of three domed sections of a complex trulli group, the masons have created a lovely valley for the rainwater to sluice into.