"Grotta di Seiano" or "Cave of Sejanus" refers to a subterranean tunnel dating to the early Roman Imperial period that was excavated into the volcanic tuff. It connected the area of what is now modern Bagnoli and the Campi Flegrei with the Gaiola Valley. Its construction is often attributed to Lucius Cocceius. It is now part of the Pausilypon Archaeological Park.
Description via Pleiades. Coordinates and heritage data from the Atika atlas.
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