The Arboretum was born in 1846 by order of Grand Duke of Tuscany Leopold II, owner of the vast Casentino forests. Realising the decline of the forest due to the continuous cutting by the people of Romagna and the negligent management of the Camaldolese monks, the Grand Duke entrusted its reordering to engineer Karl Siemon [Carlo Siemoni] who in 1846 started a collection of forest plants, both native and exotic, in order to verify their compatibility with the Tuscan-Romagnolo Apennines, in view of using them for reforesting and to obtain fine wood varieties. Today, between species and varieties, the Arboretum is made up of 137 elements, belonging to 42 families. Each entity, often represented by several specimens, is marked by a descriptive card bearing the family, scientific name, common name and area of distribution.

The Arboretum is flanked by the Museum named after Siemoni and founded in 1985. It mainly exhibits the principal spontaneous forest species and those introduced into Italy: framed dry specimens, tree trunk sections, specimens of wood attacked by insects, samples of wood of forest species. The collection also includes stuffed forest animals, typical rocks of the intact Sasso Fratino nature reserve, and relief models.

In its present location since 1992, the Museum was created to satisfy the growing demand for information about the forest environment of the Tuscan-Romagnolo Apennines, and is managed, along with the Arboretum, by the State Forest Rangers Corps.