What to see
Built by a specialised stonemason known as a trullaro or caseddaro, the structure rests directly on the limestone bedrock. The base walls, rising 1.60 to 2 metres with a 3 to 5% outward slope, were constructed without mortar. This dry-stone method was enforced by the tyrannical Count Giangirolamo II Acquaviva d'Aragona (arrested in Madrid in 1648 by Philip IV) so that dwellings could be rapidly dismantled during inspections by the Spanish viceroy, thus evading the Pragmatica de Baronibus settlement taxes. The corbelled roof requires no centering: an inner skin of thick limestone voussoirs (chianche) is covered by an outer layer of thinner, outwardly tilted slabs (chiancarelle). Crowning the roof is a hand-worked sandstone pinnacle—shaped as a disk, ball, cone, bowl, or polyhedron—acting as the stonemason's signature. The cones often feature whitewashed symbols, such as a pierced heart for Our Lady of Sorrows or the letters S, C, S, D for Saints Cosma and Damiano, to whom the local basilica is dedicated. (Note that symbols on Via Monte Pertica and the Hotel dei Trulli date to the late 20th century and 1950s). Inside, lime-plastered rooms expand by "gemmation" around a central space. Look for the arched alcoves in the thick walls, once separated by curtains for children to sleep in. To combat the cold and moisture trapped by the massive stones, interiors feature open fireplaces with hidden flues and tall chimney stacks.
Visiting
A tour of the premises illustrates how residents adapted to the waterless karst landscape. Construction always began by digging an underground cistern to collect winter rainwater; the extracted stone was then used to build the house above, with the cistern's lime-mortared barrel vault frequently supporting the floor. Unlike rural trulli, which clustered in groups of up to five or large farmyards, 19th-century notarial deeds show that urban groupings in Alberobello did not exceed two connected structures. The 19th century, driven by wine growing, marked the golden age of trulli before rising labour costs halted construction in the 20th century.
Our editors' tip
Take note of the immense 2.70-metre-thick walls. While they provide excellent insulation in summer, they cause winter condensation. Historically, inhabitants combated this by keeping doors open during the day or using a central brasero for embers (an example is kept in Alberobello's Museo del Territorio). This site vividly recalls the history of a town that reached 3,200 inhabitants before King Ferdinand IV of Naples freed it from feudal rule in 1797, leading to its declaration as a national monument on 23 September 1910.