Ospedale Psichiatrico di Volterra, a former psychiatric hospital in Tuscany, Italy, was once home to more than 6,000 mental patients.

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It was shut down in 1978 after its practices were deemed cruel.

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It was infamous for its use of electroshock therapy.

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There are reports that patients were tied to their beds in straightjackets, and letters from family were concealed.

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Many patients who were sent there never came out again, leading the hospital to be dubbed the "place of no return."

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The walls of the hospital courtyard are still covered in the carvings of a patient who was locked inside for more than a decade.

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Photographer and urban explorer Eleonora Castagnozzi, 39, ventured inside the sinister asylum.

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She said: “When I first entered I felt incredibly sad. I could empathise with the people who were locked inside this place - they must have felt so isolated."

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“I could see iron bars on all the windows and spy holes at the doors which shows they must have been supervised night and day."

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“When I walked through the decaying corridors I felt a sense of desolation and distress.”

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A mysterious series of runes, symbols and letters are scratched into the 180-metre-long courtyard walls. The frieze is the work of former patient Oreste Ferdinand Nannetti.

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Mr Nanneti was a patient at the hospital for 14 years from 1958. The hand-carved graffiti is made up of geometric shapes, words and drawings of churches and soldiers.

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Miss Castagnozzi said: “During his incarceration Mr Nannetti made a series of carved murals using his belt buckle. They are considered by some to be an artistic masterpiece.”

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The marks in the stone wall have mystified photographers, historians and psychiatrists for years.

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Many interpret his work as a manual on how to cope with hallucinations, some say they are ramblings about high-tech weaponry, spaceships and alchemy.

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