Due to its central location in the Mediterranean, Asinara was known and used by the Phoenicians, Greeks, and Romans. The Camaldolese monastery of Sant'Andrea and Castellaccio on Punta Maestra, Fornelli, possibly date back to the Middle Ages.

The island was also the target of Saracen pirate raids. Later, ownership of Asinara was contested between Pisa, the Republic of Genoa, and the Kingdom of Aragon. From the 17th century, the island was colonized by shepherds from Sardinia and Liguria. In 1721, it became the property of the Savoy Kingdom of Sardinia.

In 1885, the island became state property; by order of King Umberto I of Italy, a quarantine camp called Primario Lazzaretto del Regno d'Italia was built in Cala Reale, and an agricultural penal colony was established in Cala d’Oliva. The island became a prison island in 1885, and about 500 residents of Asinara were forced to relocate to Sardinia, where they founded the village of Stintino.

During World War I, the island was used as a prisoner-of-war camp for approximately 24,000 Austro-Hungarian soldiers, 5,000 of whom died during their captivity, mostly from cold. It was used as a detention site for Ethiopian prisoners of war during the Second Italo-Ethiopian War. Most of the Ethiopians held there were members of the Ethiopian nobility.

There used to be 12 prisons on the island. One of them, called Fornelli, was considered “the most secure prison in the world.”

In the 1970s, the prison facilities were converted into a high-security prison. In past years, it was mainly intended for members of the mafia and terrorists of the “Red Brigades,” and housed people such as mafia boss Toto Riina. At one point, a prisoner from the “Red Brigades” blew up a coffee maker, hoping to escape through the roof of the building, but failed because the roof was also made of concrete. They broke through walls to join other prisoners, barricaded themselves, and fought with police and the army, but in the end, gas was used and the uprising was suppressed.

Not all of the 12 prisons on the island were high-security; some were open prisons for inmates who also engaged in wine and cheese production and worked as shepherds. Such prisoners tried to escape to neighboring islands, but the currents and tides here were so strong that all were found dead. Only one bandit managed to escape from behind bars. Prisoner Matteo Bo escaped on a rubber boat with the help of his cellmate. There was a separate prison for sexual offenders, as other inmates attacked them.

Prisoners and guards were the only inhabitants of Asinara for about 110 years, until the prison was closed in December 1997.

In 1997, the prison was closed due to growing dissatisfaction among local residents, who disliked the gathering of the most notorious criminals and the high costs of their maintenance. The island became a national park and is currently a nature reserve. Its natural beauty, unspoiled by rare human settlements, made it an ideal candidate. Since 1999, tourists have been able to visit Asinara Island, but only through organized guided tours. Swimming is allowed only on three beaches, and private boat mooring is prohibited.

The island has many old structures, including prison facilities, as well as small settlements built for the inhabitants of the quarantine camp and for the staff who served the camp and prison. All of this has been transferred to the national park.

Sources:

https://en.wikipedia.org/wiki/Asinara