The Museum, on the first floor in the balcony of the Aldobrandesco Castle, is dedicated to the figure of David Lazzaretti (1834-1878), the "prophet of Amiata", who proposed himself as God's instrument to carry out a great reforming mission.

The human, social and spiritual story of Lazzaretti is reconstructed through the many objects that belonged to him, together with the documents and photographs, the banners and drawings of the jurisdavidic movement he founded. In the historical context of the Amiata mountain, and more generally in the history of the subaltern classes of post-unification Italy, it represented a utopian moment of great fascination and involvement. Through two specific sections: one documentary and the other an exhibition, the aim is therefore to reconstruct the events with the aid of photographs, paintings, clothing, and a vast bibliographic and archival documentation produced by the Lazzaretti movement.

David Lazzaretti's life ended abruptly in 1878 during a peaceful procession near Arcidosso at the hands of a soldier, leaving a trail of controversies and trials. His followers continued to populate the summit of Monte Labbro professing Jurisdavidism, based on a direct relationship between the social and a new era of Christianity.

The places, the characters, the experiences that characterized the religious and social life of the community are presented in a broad frame made up of iconographic material; the richness of the material produced by the "prophet of Amiata" and by the movement he founded is such as to solicit a multiplicity of interests: historical-artistic, archival, anthropological and environmental.