The region of Apulia in southern Italy is the homeland of trulli, unique stone buildings constructed in the same way as they have been built in this area since prehistoric times, practically unchanged.
Similar to Dalmatian “bunja” or Istrian “kažun”, trullo is a traditional stone dwelling built using dry stone wall technique. It was originally used as a temporary shelter for shepherds, as a storage or a shelter for livestock, but also as a permanent residence. It is recognizable by its cone-shaped roof that rises above a circular, oval, or square base. This architectural form is characteristic of the karst valley of Itria in Apulia and is associated with the tradition of building tholos, circular tombs with a dome-shaped vault. Trulli are primarily rural buildings. They can be found as individual structures or in smaller clusters throughout the valley. The only urban area characterized by this construction method is the town of Alberobello, where trulli can be found in two locations, Monti and Aia Piccola. There are more than 1500 trulli.
Completely built using the dry-stone technique, without the use of any binding agent, trulli were constructed from roughly processed pieces of limestone collected from nearby fields. The walls were very thick, ranging from eighty centimeters to over two meters, providing excellent insulation that kept the interior warm in winter and cool in summer. They were built on living rock and constructed as double walls filled with broken stones. Within these thick walls, there were ovens, hearths, or niches used for sleeping. The roof would begin at a height of about two meters from ground level. The roof was also made of two layers; the inner structural layer was constructed as a dome with a keystone, while the outer layer, made of stone slabs gently sloping outwards, provided protection from rain.
The stone slabs of the outer layer could be replaced without compromising the stability of the building. At the top of the roof, there would usually be a pinnacle, a carved stone in the shape of a cone. The trullo is a traditional Apulian dry stone hut with a conical roof, shaped like a ball, disk, cone, or some other distinctive shape; it is assumed that this is the signature of the master who built the trullo.
The windows were small, and some light would filter through the ventilation opening at the top of the roof and through the door, making the interior of the trullo quite dark. Most of them had only one room, with niches in the walls that provided additional space. In some larger ones, there was also an upper floor or gallery with a wooden floor, and additional space was usually obtained by adding a new trullo connected to the main one with a low passage with an arch. Trullo of circular shape was usually built as a single building, but when grouped together, their layout was often rectangular. A larger number of interconnected trulli is called trulleria, where alongside residential buildings, there were also animal shelters, forming a series of smaller courtyards and enclosed gardens and vegetable gardens that were accessible only from the houses. Although the construction of this or a similar type in Apulia had been present much earlier, the first trulli date back to the 16th century when scattered settlements gradually began to merge into larger rural communities. This is how Monti and Aja Piccola were formed in today’s Alberobello. In the mid-16th century, there were about forty trulli in the Monti area, but from the beginning of the 17th century, after the construction of a mill, bakery, and inn, the settlement expanded, and by the late 18th century, it had over 3500 inhabitants. In 1797, feudal authority was abolished, and since then the construction of new trulli has rapidly declined. Today, Alberobello is unique, among other things, because its Monti and Aja Piccola locations are the only examples where dry stone architecture has transcended its natural rural framework and taken on an urban form, with all the characteristics that define a city, making them among the most significant and best-preserved permanently inhabited spontaneous urban settlements in Europe. Because of all this, in 1996, the trulli in Alberobello were inscribed on UNESCO’s list. World Heritage List with the following rationale: “The locality has exceptional universal value as an outstanding example of architectural construction created using prehistoric building techniques that have remained intact and effective in the modern world.”