A trullo is a traditional stone building constructed from limestone and featuring a cone shaped roof. It is built with extremely thick walls, using a technique that doesn't require mortar between the stones. Trulli were built to be used as homes or for storage, and many are still in use today for various purposes. They are usually found in a region of Italy known as Apulia.
The walls of a trullo are usually built from thick blocks of locally available limestone. They are often up to 6.5 feet (2 m) thick, which provides an insulating effect that keeps the interior much cooler than the outdoors in the hot summers and warmer in the winter. There is usually a central room, with other smaller living areas built off it. Trulli usually have one floor; those with a second story are quite rare.
The buildings are most often constructed in a square shape, with a domed roof that is built up into a cone near the top and with a decorative spire at the peak. The walls of a trullo are typically whitewashed, and the conical roof often has symbolic decorations painted onto the natural stone. These decorations are selected for a variety of reasons, and may feature religious or pagan symbols.
Typically, a trullo is assembled using a technique that requires no mortar or cement between the stones, called "a seco" in Italian. Folklore concerning this revolve around the common theme that they are built in this manner to evade taxes. Without mortar, the buildings could be quickly taken apart when the property assessor was coming, so that it appeared that there was nothing to tax!
Some surviving structures are hundreds of years old; the thick walls are very sturdy even without mortar. A trullo was often built to serve as housing for farm workers. Another common use was for storing grain and wine. Today, many of the surviving trulli have been restored, and they're often used for upscale tourist lodging.
Traditionally, the trullo was built in the Apulia region of Italy, or Puglia in Italian, in the Itria Valley. With thousands of trulli all over the region, there are several towns with an abundance of them, including Alberobello, Fasano, Cisternino, and others. There are also a few examples of trulli in the wine regions of Germany, believed to have been built by wine workers from Apulia, that have stood for centuries.