Underground Naples: Discovering the City Beneath the City

Beneath the lively streets of Naples, there’s a hidden world that most visitors never even realize exists. This vast network of tunnels, caverns, and ancient structures—Underground Naples—sprawls beneath the entire historic center, plunging as deep as 40 meters.

When I visited, I wandered through this subterranean labyrinth and honestly, I couldn’t believe how much history sits just underfoot. Underground Naples doesn’t just support the city above—it preserves 2,400 years of stories, secrets, and memories.

As I moved along the dim, tuff-stone corridors, I felt like I was slipping through different eras. The tour lasted a little over an hour, but it packed in centuries of Neapolitan life.

People have used these spaces for everything—Roman aqueducts, WWII bomb shelters, even secret passageways. What really stuck with me was how the underground city almost mirrors the one above, creating what locals call “the negative of the city on surface.”

If you’re headed to Naples, you really shouldn’t skip this underground adventure. Locals and tourists both rave about it, and I totally get why.

The cool air down there is a relief during the hot months, and those ancient chambers? They offer a side of Naples you just won’t see anywhere else. Wear comfy shoes, maybe bring a jacket, and be ready for the underground’s own mysterious climate.

The Origins of Underground Naples

Naples hides an ancient world just beneath its busy streets. Over centuries, each civilization layered new purposes and secrets into this subterranean maze.

From Greek Settlers to Parthenope

When I first explored Underground Naples, I learned that Greek settlers started it all around the 8th century BCE. They founded Parthenope, which later became Neapolis, or “new city.”

The Greeks dug out the soft volcanic tuff stone below the city for building. That’s how they created the earliest underground chambers and corridors.

They weren’t just digging for stone—they used these spaces for storage too. As I walked through the ancient tunnels, I could almost picture those early settlers at work.

As the city grew, these underground spaces became more important. They supported the bustling life above in ways I hadn’t expected.

Roman Influence and Urban Evolution

The Romans came along and took the underground network to another level during the Augustan era. I found out they built a mind-blowing system of aqueducts, channeling water from the Serino springs—70 kilometers away!

This engineering feat brought water to public fountains, baths, and rich homes all over Naples. The Romans also tunneled roads to link Naples with nearby towns.

Markets and storage areas popped up underground. Later, people turned some of these spaces into cisterns and reservoirs.

The Romans really wove these underground elements right into daily city life. Their urban planning was just next-level.

Formation of Ancient Tunnels and Passages

The Naples labyrinth didn’t just happen by chance. As I squeezed through the tunnels, guides explained that each one had a job—water management, transport, storage.

The soft, yellow tuff stone made digging easy, so workers carved out rooms and cisterns with simple tools. Over hundreds of years, the network just kept growing.

During wars or uprisings, people used these spaces as shelters and escape routes. It’s wild to realize that so many modern buildings in Naples still rest on these ancient tunnels.

Generations kept adapting and expanding the underground, and now it’s one of the world’s largest subterranean networks. That’s some serious human creativity.

Exploring the Iconic Sites Beneath the Surface

Naples hides an entire world below its energetic streets. The underground stretches under the historic center, revealing layers of history all the way back to ancient Greece.

Napoli Sotterranea: The Classic Experience

For my first real taste of underground Naples, I joined a Napoli Sotterranea tour. This sprawling maze of tunnels and chambers sits about 40 meters below the city.

A guide led us through narrow walkways carved out of yellow tuff, where the Greeks once built aqueducts. Later, these same passages became WWII air raid shelters.

What really blew me away? The traces of Roman daily life—cisterns, water tanks, even old theater spaces, all hidden beneath the city.

It stays cool down there, so a jacket comes in handy, even in July. Some corridors get pretty tight, but the guides hand out candles for certain stretches, which makes it feel like a real adventure.

San Lorenzo Maggiore and the Ancient Roman Forum

Under the San Lorenzo Maggiore basilica, I wandered through a real Roman marketplace from the first century.

The excavation uncovered shops, bakeries, and a treasury, all perfectly preserved. It’s surreal to walk where ancient Romans once haggled and shopped.

What’s wild is how the site connects to the church above. You can literally see layers of history stacked up—medieval walls right on top of Roman ones.

A small museum nearby shows off pottery and coins found during digs. It’s a cool way to trace Naples’ growth from the ground up.

Bourbon Tunnel: A Royal Escape Route

The Bourbon Tunnel (Galleria Borbonica) feels totally different from the other sites. King Ferdinand II had it built in 1853 as an escape route from the Royal Palace to army barracks.

Inside, I found vintage cars and motorcycles from the 1940s and ’50s. They’d been abandoned when the tunnel doubled as a police impound lot.

During WWII, the tunnel protected people from bombs. Seeing old beds, toys, and graffiti left behind was honestly moving.

The massive cisterns once supplied water to Naples. They’re so big, people even hold concerts down there now and then.

The Hidden Roman Theater and Summa Cavea

I ducked through an ordinary doorway in the Anticaglia district and ended up in Naples’ ancient Roman theater. Most of this first-century spot still hides beneath modern buildings.

The visible Summa Cavea (upper seating area) hints at how grand the place once was. Emperor Nero performed here in 64 AD—imagine that!

What really makes this site special? Locals have built their homes right into the ruins. In some apartments, Roman columns literally hold up the ceiling.

My guide showed me how people enter their basements through gaps in the old theater walls. This mix of ancient and modern life just feels so… Neapolitan.

Catacombs and Mysterious Burial Grounds

Naples’ underground isn’t just about tunnels and aqueducts. This city also hides burial grounds where death, art, and faith all intertwine.

Catacombs of San Gennaro: Naples’ Spiritual Heart

The Catacombs of San Gennaro blew me away—they’re the most important underground burial site in southern Italy. Walking through the tunnels, I marveled at the two-level structure dating back to the second century CE.

Upstairs, I spotted frescoes and mosaics that somehow survived centuries underground. Early Christians arranged their graves around the tomb of San Gennaro, Naples’ beloved patron saint.

The underground basilica is jaw-dropping, with high ceilings and grand arches. Local guides explained that people used these catacombs for burials and worship until the 10th century.

Catacombs of San Gaudioso: Art and Devotion

The Catacombs of San Gaudioso, tucked beneath the Basilica of Santa Maria della Sanità, show a quirky Neapolitan approach to death. They’re smaller than San Gennaro’s, but honestly just as fascinating.

What sticks in my mind are the skull niches—wall paintings with actual skulls set into the art. Nobles appear in their finest clothes, with their real skulls completing the portraits. It’s a little eerie, but also beautiful in its own way.

San Gaudioso, a North African bishop, ended up here in the fifth century after fleeing persecution. The catacombs became a pilgrimage site, and the frescoes inside show off scenes in a Byzantine style.

Fontanelle Cemetery and Ancient Rituals

In Sanità, I stumbled into the Fontanelle Cemetery, once a tufa quarry turned ossuary in the 17th century. Thousands of anonymous skulls and bones fill the space—it’s haunting, but oddly peaceful.

Locals developed the “anime pezzentelle” ritual here, where people would “adopt” a skull, pray for the unknown soul, and ask for favors in return. It’s a unique connection between the living and the dead.

The cemetery holds victims from the 1656 plague and later cholera outbreaks. Despite the grim contents, the atmosphere feels more tranquil than scary.

Underground Cemetery of Santa Maria della Sanità

Beneath the baroque Santa Maria della Sanità church, I explored another of Naples’ fascinating burial sites. This underground cemetery ties directly into the neighborhood’s identity.

Builders constructed the church right above ancient Christian burial grounds, keeping a link with the sacred spaces below. Light from above filters down, giving the chambers a soft, otherworldly glow.

Family tombs and religious art fill the cemetery, some dating back centuries. Locals still honor these places, visiting and praying for ancestors.

Unlike some archaeological sites that feel frozen in time, this one stays woven into everyday Naples.

World War II Relics and Cultural Layers

Naples’ underground tells the city’s history in layers, and World War II left some of the most powerful marks. What once served as ancient aqueducts became bomb shelters, and now, cultural treasures.

Air-Raid Shelters and Wartime Refuges

During WWII, Naples suffered heavy bombing, and people fled underground for safety. The old Greek-Roman aqueducts and cisterns saved thousands of lives.

I came across children’s toys, family photos, and religious icons—little things people clung to for comfort. Guides pointed out graffiti and scribbles left by families who waited out the raids.

Basements under regular buildings turned into organized shelters, with sleeping areas, basic toilets, and makeshift ventilation. Some even had multiple entrances for quick escapes.

Transformation Into Modern-Day Exhibitions

Today, these tunnels have become museums and exhibitions. Walking through, I saw how curators kept the original feel while adding displays.

Vintage cars abandoned underground now serve as quirky exhibits. Some were hidden during the war, others just forgotten over time.

I spotted gas masks, ration cards, and military gear, all arranged to show what daily life looked like during the conflict. Some tunnels play air raid siren sounds—it’s pretty immersive.

Photos line the walls, showing Naples before and after bombings. They really drive home why these underground spaces mattered so much.

Archaeological Discoveries and Art Installations

Explorers keep finding new layers under Naples—Greek and Roman artifacts sit right next to medieval walls and WWII relics.

Some artists have started using these spaces for installations. I saw light shows in old cisterns that made the whole place feel magical.

Recent digs turned up rooms with Roman mosaics just steps away from wartime graffiti. It’s wild to see so many eras collide in one place.

Cultural events happen underground all year. I caught a haunting concert in an old air raid shelter, and the acoustics in those stone chambers made it unforgettable.

Planning Your Underground Adventure

Diving into Naples’ hidden world takes a little planning, but it’s so worth it. Knowing what to expect helps you make the most of your time below ground.

Guided Tours: What to Expect

In my experience, guided tours are the way to go. Most last about 60–90 minutes and take you through Greek-Roman aqueducts, WWII shelters, and centuries-old tunnels.

Guides usually speak several languages, and English tours run multiple times a day. My guide shared stories about how Neapolitans survived and adapted underground.

It stays 15–18°C (59–64°F) year-round, so a light jacket is smart. Some tunnels get tight and dark, but honestly, that’s part of the fun. Most tours start near the Duomo, so you can easily find them after checking out the cathedral.

Tickets and Booking Tips

Tickets usually cost €10–15 for adults, with discounts for students and kids. I’d definitely book online ahead of time, especially from May to September when tours fill up fast.

A few groups run tours:

• Napoli Sotterranea (the classic)
• Galleria Borbonica (Bourbon Tunnel)
• San Lorenzo Maggiore (archaeological site)

Booking a day or two in advance worked well for me. Some tours offer combo tickets with other Naples attractions, which saves you money and hassle.

I liked going in the morning—fewer crowds underground. Most places take credit cards, but carrying some cash never hurts in Naples.

Accessibility and Practical Travel Advice

Underground Naples isn’t super accessible if you have mobility issues. Expect narrow tunnels and lots of stairs. Most tour companies mention these limits on their websites.

Wear sturdy shoes. I wore sandals once and instantly regretted it on the uneven ground.

Getting to the main sites is easy by public transport. Metro Line 1 stops at “Museo” and “Università,” both close to popular entrances.

If you can, visit the underground early in your trip. It gives you a whole new perspective on everything you see above ground afterward.