Trulli of Alberobello

The trulli of Alberobello are small houses in the Puglia region of southern Italy built without mortar from roughly worked local limestone and topped by distinctive conical stone roofs. The town holds the largest concentration of these buildings, and the ensemble is inscribed on the UNESCO World Heritage List under criteria (iii), (iv) and (v) as an outstanding example of a vernacular settlement that keeps much of its original form.

The stone used for a trullo usually came from the house site itself, dug out while forming the cistern below the floor, or from boulders and outcrops cleared from surrounding fields. That made the building method a direct expression of local geology and farming.

How the roof is built

A trullo roof is a corbelled structure, not a true arch or vault. Each course of stone projects slightly inward over the course below until the opening closes at the top. The roof has two skins:

• An inner dome of wedge-shaped stones, closed by a single capstone.
• An outer cone of thin, overlapping limestone slabs known locally as chianche or chiancarelle, laid so that rainwater runs off.

The walls below are also dry-stone, built as two faces with a rubble core and finished with whitewash. Many cones carry a carved pinnacle at the apex, and some are painted with symbols in white.

Water management

The roofs are part of a rainwater system. Projecting eaves gather runoff and lead it through a channelled slab into a cistern beneath the house, which mattered in a karst landscape with little surface water.

History and protection

According to the UNESCO listing, the oldest surviving structures date from as early as the mid-14th century, and the building of new trulli declined after feudal rule ended in 1797. Individual parts of the town gained Italian protection long before world heritage status: the Trullo Sovrano was declared a national monument in 1923, and the Rione Monti district followed in 1928. The protected property covers about 11 hectares (27 acres) in six parcels, including the Rione Monti and Rione Aia Piccola districts, with more than 1,500 trulli.

Maintenance today

Because the cone is made of loose-laid slabs, repairs involve resetting or replacing individual stones rather than applying a membrane. Conservation practice aims to keep the dry-stone technique, the local limestone and the whitewashed walls so that the townscape remains authentic.