The chestnut is a long-living tree that can reach remarkable size in diameter if cultivated or standing alone. A number of giant chestnut trees are reported throughout Europe, even if no systematic inventory exists. In southern Switzerland a systematic inventory of the giant chestnuts has now been attempted for the first time. In our definition, a chestnut is considered a monumental tree when it is larger than 7 m in girth at a mean height of 130 cm above ground level. A total of 300 individuals were registered. The giant individuals are not randomly distributed, and the trees are concentrated in and around the mountain settlements between 700 m (lower anthropic limit) and 1000 m a.s.l. (upper ecological limit). Unfortunately, most of them are in bad phytosanitary shape and the stems are usually hollow. With this approach, we hope in the future to improve our knowledge of settlement history and landscape evolution in southern Switzerland since the Middle Ages.