Santo Stefano is an island in the Tyrrhenian Sea off the west coast of Italy, and part of the Pontine Islands. It is roughly circular, with a diameter of less than 400 metres, and it is located 2 kilometres east of the nearby island of Ventotene. From 1797 to 1965, it was the site of the Santo Stefano Prison.
Description via Wikipedia. Coordinates and heritage data from the Atika atlas.
Atika pings you when you walk or drive past heritage like this. Works offline, no account needed to explore.