Here, in fact, in the Middle Ages, a community of Benedictine monks gave life to a flourishing ceramic production activity, taking advantage of the particular clayey conformation of the territory. Today there are numerous artisan shops located along the streets of the village. Many valuable pieces produced in Castelli are exhibited in the best museums in the world, the Louvre in Paris, the Metropolitan Museum of Arts in New York, the British Museum in London, Palazzo Venezia in Rome and many others. A modern and efficient Art Institute, located in the upper part of the town, prepares young people to always keep alive the great artistic and artisan tradition of Castelli.

A short distance from the town, the church of San Donato with a 17th-century ceiling with majolica bricks, defined by Carlo Levi as the Sistine Chapel of Italian majolica is worth seeing: 780 bricks decorated with profiles, coats of arms, astronomical symbols, animals and floral motifs in bright colors . Inside the parish church there is a valuable medieval wooden statue of the Madonna with Child and a mid-century majolica altarpiece. The ceramics museum, located in a former convent, preserves a priceless collection of ancient ceramics.