Crypts. Bunkers. Secret tunnels. Hidden basements. Fallout shelters. Underneath every historic city is another city, a hidden city, with its own history and its own residents. The older the city, the more lies beneath the surface.

I’ve always been fascinated with the underground world, whether it’s caves or the ancient subterranean cities of Cappadocia. Living in Spain, I’ve been fortunate to explore the tunnels underneath many of Europe’s capitals. Here are a few worth visiting.

Rome

Besides countless crypts beneath the city’s ancient churches, there’s a whole city of the dead under the Appian Way. Actually more than one. Several networks of early Christian catacombs are open for visitors, but even the longest tour will show you only a fraction of twenty kilometers of tunnels. Most are narrow and crudely carved, with niches in the walls to house the estimated 500,000 bodies that were buried here. All tours are guided, both to keep visitors from getting lost in the labyrinthine passageways and keeping them from being tempted to open the few graves that are still sealed.

The catacombs date to the 2nd and 3rd centuries AD, when Christianity was coming into its own as a major religion in the Roman Empire. Christians weren’t always persecuted–that depended on who was the emperor–but they felt it best to keep out of sight and so buried their dead in this network of passages. They also worshiped down here and you can see the simple rooms that acted as churches. The constant temperatures in tombs and churches have preserved some of the earliest Christian art, including a Last Supper painted 1,800 years ago.

Tallinn

Estonia boasts the oldest capital in Europe, so it’s no surprise it has some secrets under the flagstones. The Bastion Tunnels have recently been opened to the public. Part of the old fortifications built by the Swedes during the 1670s when they controlled the region, they’re a series of tunnels running underneath the city’s old ring of earthworks. The entrance is under the Kiek in de Kök castle and museum, which offers interesting displays about medieval Tallinn plus fine views of the city.

The tunnels were abandoned in the early modern era, and explored only by brave and desperate individuals lured by stories of hidden treasure. They were reopened in the 1930s to be used as an air raid shelter and saved countless lives during World War Two. During the Cold War they became fallout shelters. They again fell into disuse sometime in the 1980s because the Soviets realized they were too close to the surface to protect against a nuclear strike. In the 1980s and 90s they became a hangout for punk rockers and homeless people. You can learn all about this on a fascinating tour through the tunnels.

London

London has done a good job turning its underground world into major attractions. The most popular is the Churchill War Rooms. An essential stop for history buffs, this set of bunkers, from which Churchill helped win WWII, has been left exactly the way it was on VJ Day. Walking through here can be a bit spooky; you can almost hear the low rumble of the Blitz on the streets above and the discussion of strategy among the men and women who worked down here. The map room, Churchill’s bedroom, the cabinet room, and the phone room from which the prime minister consulted President Roosevelt are all quite interesting and atmospheric.

The Guildhall Art Gallery has a fine collection of more than 4,000 paintings collected over four centuries. The ornate building sits atop a Roman amphitheater, so head downstairs and into a passage beneath Guildhall Yard to see the remains of what used to be the largest Roman amphitheater north of the Alps.

Many of London’s churches have interesting crypts. Not far from the Guildhall is St. Bride’s where beneath the 17th century church you can see the decorated tile floor of a Roman building as well as a Saxon church dating to the 6th century. It is believed there was a Celtic Christian church here even earlier, perhaps one of the earliest Christian communities in the British Isles.

Istanbul

Located on the European side of the Bosphorus, the old quarter of Istanbul used to be Constantinople, the capital of the Byzantine Empire. Constantinople survived numerous sieges and they did this with a combination of massive city walls and a ready supply of fresh water. Some of this supply was stored in the Basilica Cistern. Built by the Emperor Justinian I (ruled 527-565) to supply water for his personal palace and other important buildings in the neighborhood, it still being used in the late 19th century.

Descending from the bustling city into this place is an eerie experience. It’s still partially filled with water, its high roof held up by 336 marble columns in various styles. Strolling along the walkways over the water and studying these columns makes for an unusual artistic experience, and if you’re visiting Istanbul in the hot months the cool, damp air will be a welcome relief.

So the next time you’re visiting one of Europe’s capitals, don’t just see the sights, see what’s under them!

Author bio:
Chris is one of the co-founders of travayl.com, a social travel photo site. When he’s not busy trying to simplify trip planning, he’s trying to maintain his status as a part-time travel ninja.

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