This nature reserve was founded in 1923 in the very heart of the massif to protect the fauna, flora and landscapes of the region. It extends over an area of around 100 000 acres, not including the 11 119 acres of the Mainarde territory (in the Molise region) and is surrounded by an external protected area of 150 000 acres. Two-thirds of the park is made up of forests (mainly beech, maple, oak and black pine), and it offers a last refuge to animals that once lived all over the Apennine range: brown bears, wolves, otters, martens, royal eagles.