While Rome is pushing forward with its long-awaited Metro Line C — a new subway line whose construction keeps turning up unexpected archaeological finds right under the city center — the monument we’re featuring here owes nothing to those excavations. It has always been there, within arm’s reach, but like so many Roman sites, quietly “forgotten.” It took a decisive push from modern technology to make it come back to life.

The Basilica of Neptune — spaces closed for centuries, tucked behind the famous Pantheon, is not the center of a dedicated guided visit called “Beyond the Pantheon”, giving visitors access to this once abandoned monument, now returned to anyone willing to look past the usual postcard.

 

The Basilica of Neptune is not a name you’ll find in standard travel guides. Nonetheless, it has existed for over two thousand years. It was built by Marcus Vipsanius Agrippa around 25 BC — yes, the same Agrippa who commissioned the Pantheon itself.

Compared to its more famous neighbor, the Basilica had a far rougher ride through history. Caught in the fire of 80 AD that devastated the Campo Marzio district, it was rebuilt by Emperor Hadrian, but a roof collapse in the 13th century set off an irreversible decline. Over the following centuries it was progressively stripped for building materials — as happened to so many ancient structures in Rome — until in the 16th century the Palace of the Ecclesiastical Academy was built over its remains. What survives today lies seven meters below street level, sheltered in what Romans call the Fossato del Diavolo (“Devil’s Moat”), a trench opened in 1881.

Visitors today won’t see the building as it originally looked, but the painstaking work of archaeologists and filmmakers has transformed these spaces — ravaged by centuries of plundering — into powerful evidence of the archaeological richness buried beneath this part of Rome.

It may sound obvious, but the reopening of the Basilica of Neptune is a reminder of just how much is hidden in this one area of Rome — a neighborhood that tourists have always associated with what they can see and touch: the baroque churches, the winding alleys, the fountains… and of course the Pantheon itself. For those who want to look beyond the obvious, this stretch of the Campo Marzio holds layer upon layer of history still waiting to be told.

A striking example is the , less than two hundred meters from the Pantheon and the Basilica di Nettuno. The name says it all. Sopra Minerva is a literal description. This church, the only surviving example of Gothic architecture in Rome, stands on the remains of a vast sacred complex from the Roman era that included the Temple of Minerva Chalcidica, the Temple of Isis, and the Temple of Serapis.

A short walk away, the — yes, the one with the cats! — tells the story not only of Caesar’s assassination but of Rome’s growing economic power before the Imperial age. And just along Via delle Botteghe Oscure, the publicly accessible excavations of the Crypta Balbi are revealing a series of monuments long thought lost forever. And all of this is just the tip of the proverbial iceberg!

The “Beyond the Pantheon” tour runs every day except the first Sunday of the month, in capped groups of no more than 25 people. Each visit lasts about 45 minutes and is led by a guide. Tickets cost €10 for the Basilica of Neptune visit, plus €5 if you also want to enter the Pantheon through a dedicated internal passage.

Where to buy tickets: online only, through the Musei Italiani app and platform (available on iOS and Android) or via the direct link: . Booking ahead is strongly recommended as spots are limited.

Time slots (but we do recommend to always check the official site before booking):

Entrance address: Via della Palombella — not the Pantheon’s main entrance, but the street running behind the Rotunda.

Getting there by public transit: the most convenient landmark is Largo di Torre Argentina, one of the main bus hubs in Rome’s historic center, well connected to Termini station and other parts of the city. From there, it’s a pleasant flat walk of under 10 minutes to the Pantheon.

Accessibility note: the Basilica of Neptune is accessed seven meters below street level, but an internal elevator — completed in 2024 — is available for visitors with limited mobility or those traveling with a stroller. It’s worth checking in advance that it’s in service by calling +39 06 39 96 79 50.