The main characteristic of Sappada is its concentration of houses in 15 clusters or villages (héivilan), arranged in an almost regular sequence along the sunny side of the valley. They correspond to the family groups that colonized the valley starting, presumably, in the IX or X century (a document dating from 1296 makes reference to a fee paid by the community "since ancient times").
Today, Sappada/Plodn still preserves obvious traces of its origins, as a precious example of a German linguistic island. In fact, a unique dialect based on an ancient pocket of medieval German survives here. Compared to modern German, it stopped evolving around the XIII century.
Sappada combines its linguistic identity with the distinct style of its buildings, characterized by structures made of joint horizontal beams on a masonry base. The houses all have the same layout. They always have a central corridor with two rooms on one side or four rooms two on each side. They have two or occasionally three floors, and frequently include later side additions.
The house (Haus) is complemented by the stable/hay-loft (Štol), with special spaces for sheltering the animals (base part), storing the hay (top part), and drying the cereals (external balconies).
The single architectural entities are clustered together in small urban units called borgate (villages), all of which have common architectural features such as chapels (màindlan), crucifixes (khràizen) and fountains (trégher), reflecting the community's way of life.
In 1922, the construction of a new road, parallel to the old one but straighter and at a lower elevation, created better circulation and new opportunities for urban development. Thus, the new road indirectly contributed to safeguarding the identity and the architectural patrimony of the ancient villages.