A trullo is a traditional Apulian dry stone hut with a conical roof. Their style of construction is specific to the Itria Valley, in the Murge area of the Italian region of Apulia. Trulli were generally built as temporary field shelters and storehouses or as permanent dwellings by small proprietors or agricultural labourers.
In the town of Alberobello, in the province of Bari, whole districts are packed with trulli.
The golden age of trulli was the 19th century, especially its final decades marked by the development of wine growing. Traditionally trulli were built using dry stone masonry, without any mortar or cement. This style of construction is also prevalent in the surrounding countryside where most of the fields are separated by dry-stone walls. The roofs are constructed in two skins: an inner skin of limestone voussoirs, capped by a closing stone, and an outer skin of limestone slabs that are slightly tilted outwardly, ensuring that the structure is watertight. The roof stones can be taken away without compromising the stability of the rest. In Alberobello atop a trullo’s cone there is normally a hand-worked sandstone pinnacle (pinnacolo), that may be one of many designs – disk, ball, cone, bowl, polyhedron, or a combination thereof, and is supposed to be the signature of the stonemason who built the trullo. Owing to the concentration of houses, trulli have few openings outside their doorway and a small aperture provided in the roof cone for ventilation.
There are many theories behind the origin of the design. One of the more popular theories is that due to high taxation on property the people of Apulia created dry wall constructions so that they could be dismantled when inspectors were in the area.