Alberobello is known as the Capital of the Trulli. The trullo is a fascinating architectural feature of this area of Puglia, a building with conical roof made without mortar. Alberobello has special status internationally - designated a UNESCO world heritage site - because its collection of some 1,500 trulli in an urban environment is unique. Some of the trulli are now used for stores, restaurants, and lodging. But many are still inhabited by locals, who are very friendly to visitors. As a world heritage site, Alberobello is a tourist attraction, but as it is less accessible from the tourist-heavy west coast, it is not overrun by tourists, and most tourists of Alberobello are Italians. The town is the centre of an annual pilgrimage to the Basilica dedicated to the martyr saints Cosma and Damiano. In summer Alberobello plays host to a number of festivals. These include a significant international folk festival, music festivals including classical, jazz and popular music, dance, theatre, street theatre and childrens events. There are also religious festivals with music performances and firework displays. Most of the performances are free and open-air. The town has a vibrant passeggiata with summer strolls continuing beyond midnight.