Pianosa

Pianosa is a small (about 10 km²) island in Italy's Tuscan Archipelago. The name is derived from the Italian word "pianura" (plain) because its highest point is some 22 meters over sea level. It was known as Planasia in the ancient Roman era.Pianosa has no permanent residents. It is known in Italy for hosting a maximum-security prison, where especially dangerous Mafia criminals are held. It is also historically significant for Augustus banishing his grandson and ex-heir Postumus Agrippa there in AD 6 or 7. Postumus remained there until his execution around the time of Augustus's death in 14.
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