Archaeological park of Posillipo

Is it worth the trip?

When it is open, yes, if you are in Naples. A Roman theatre and odeon on a cliff over the bay, reached by a Roman tunnel nearly 800 m long, is a striking combination, and the escorted entry cost nothing before the closure. It is still not a place to drop in on: there is no walk-in visit, only booked visits that start from the tunnel at fixed times, and the restoration works already left the theatre area only partly open before the park shut (the operator).

For now, though, the honest answer is that you cannot go in. The operator announced the closure from 1 October 2026 without a date for reopening, so check gaiola.org before building a day around it.

Getting there

Every visit starts at the entrance to the Grotta di Seiano, Discesa Coroglio 36, on the Bagnoli side of the hill (the operator). An ANM bus stop, “Discesa Coroglio - Grotta Seiano”, is mapped a few metres from the tunnel mouth, and there are car parks about 150 m away (OpenStreetMap). The theatre itself is about 0.9 km in a straight line from the entrance, on the other side of the hill, and you do not reach it by any other way on a public visit.

Before the closure, visits ran Tuesday to Sunday and had to be booked online at gaiola.org. The escorted entry without a guide left at 09.15, took about an hour and was free. Guided visits, about an hour and a half, left at 11.00 from Tuesday to Friday and at 10.30 and 12.15 on Saturdays, Sundays and holidays, and cost €7 for adults and €4 for children aged 7 to 14, free up to 6. During the works visitors also signed a liability waiver sent with the booking, and the park closed whenever a weather alert was in force (gaiola.org, read 19 October 2026). Expect the arrangements to change when it reopens.

History

After the battle of Actium in 31 BC, Vedius Pollio chose the stretch of coast between the Gaiola and the bay of Trentaremi, known as Pausilypon, “relief from pain”, for his retreat. Beside the villa he built the theatre, the odeon, a nymphaeum and a bath complex. When he died in 15 BC the villa passed to Augustus and became a residence of the emperors; Hadrian is named as the last of them to live there (it.wikipedia). Pleiades records Pausilipum as an ancient Graeco-Roman settlement on the Bay of Naples.

The tunnel is named after Sejanus, Tiberius’s prefect, who by tradition had it widened and put in order in the 1st century AD. The first cut is attributed to the architect Lucius Cocceius Auctus, working for Marcus Agrippa some fifty years earlier, to link Pollio’s villa and the other villas of Pausilypon with the ports of Puteoli and Cumae (it.wikipedia; Pleiades notes the attribution to Cocceius as the usual one). It fell out of use and was forgotten until roadworks uncovered it by chance in 1841; Ferdinand II of Bourbon had it cleared and opened, and it became a tourist sight. In the Second World War it served the people of Bagnoli as an air-raid shelter, and war damage and landslides in the 1950s left it abandoned again (it.wikipedia).

The park reopened to the public after restoration in 2009, with the Centro Studi Interdisciplinari Gaiola running the guided itineraries (it.wikipedia). The visits are organised with the Soprintendenza Archeologia, Belle Arti e Paesaggio for the city of Naples (the operator).

A little further along the coast, near Marechiaro, the ruin known as the Palazzo degli Spiriti is described as part of a nymphaeum belonging to the same villa; some read its sunken basins as a fishpond for moray eels (it.wikipedia).