Plants as arbutus, Myrtus, pistacia lentiscus, mock privet, Mediterranean buckthorn, juniperus phoenicea and limonium sommierianum knew only on Isola del Giglio and Montecristo, grow up on the island.

[6] Giannutri was abandoned for mysterious reasons from the 3rd century until 805 when Charlemagne donated to the Tre Fontane Abbey some lands, including the island which returned to be inhabited by cenobitic monks and some hermits.

In the following centuries the Island was assigned by emphyteusis to the Aldobrandeschi family of Sovana in 1269, to the Orsini of Pitigliano on June 15, 1410 and to Siena on August 12, 1452 by Pope Nicholas V award.

[7] The island changed several times of rule: Spanish, French and German and for sometimes became refuge of pirates and Saracens until the Treaty of Lunéville which assigned Giannutri to the Kingdom of Etruria in 1801, afterward to the Grand Duchy of Tuscany till the Italian unification in 1861.

[8] The Minister of Finances Quintino Sella, with a Royal decree, donated the island to the Comune of Giglio in 1865 in order to settle a farm.

The Società Porto Romano declared bankruptcy and the numerous owners of the houses were obliged to form a society, called Libero Consorzio Giannutri, in order to administer the island.

The Calidarium, formed by a rectangular room from whose walls passed the warm air, was placed halfway between the Villa and Cala Maestra and was richly adorned with marbles and mosaic floor.