This top tourist spot has a secret tunnel city, lost for over a century — visitors will soon be able to see it for the first time

A top travel destination has uncovered an ancient secret.

A little-known network of subterranean passageways hidden beneath Rome’s Capitoline Hill — holding clues to a long-ago chapter of the Eternal City’s past — will reportedly soon open to visitors.

“No one has seen these caves and tunnels for more than a century,” archaeologist Ersilia D’Ambrosio said.

This vast underground complex — covering 42,000 square feet — hides out beneath some of the city’s top attractions, steps from the Roman Forum and the 2,000-year-old Teatro di Marcello.

Known as the Grottino del Campidoglio, or Capitoline Grotto, these tunnels were once filled with life during the days of Julius Caesar.

Long before it was sealed off by Benito Mussolini in the 1920s, it served as a quarry, cistern, tavern, bomb shelter, and even a bustling subterranean marketplace during the 19th century.

Now, thanks to a massive $2.8 million restoration project, the tunnels are set to reopen to the public in late 2026 or early 2027.

CNN was granted exclusive access earlier this month.

About 75 feet below ground, visitors found the cool, damp tunnels at a constant 55 degrees Fahrenheit —despite the sweltering 95-degree summer heat.

At its deepest point, the grotto plunges almost 1,000 feet below the surface — deeper than most subway tunnels.

“This is an esoteric experience in many ways,” D’Ambrosio explained.

She noted that every day researchers are on site, new discoveries come to light, like marble foundations from the Temple of Jupiter, ancient animal tethering rings, or pots likely once filled with wine and olive oil.

The Grottino’s history spans millennia. From ancient stone quarries to medieval shelters and 19th-century taverns, the tunnels evolved alongside Rome. During World War II, parts were used as air raid shelters, complete with fortified doors and public bathrooms still marked “gabinetto.”

German writer Johann Wolfgang von Goethe is believed to have fallen in love with a tavern worker here in the 1780s, immortalizing the moment in his famed “Italian Journey.”

Despite the area above undergoing major renovations in recent decades — including the nearby Roman and Imperial Forums — these tunnels remained sealed. Now, thanks to modern technology, the passageways are finally safe for public exploration.

Laser scanning, structural reinforcements, and radon gas ventilation systems are being installed to prepare for future tours. Specialized air filters and a guided-only entry system will ensure both visitor safety and preservation of the fragile complex.

When it opens, the grotto will feature museum exhibits, artifacts recovered from previous digs, and possibly even pieces from the Capitoline Museum’s personal archives. Disabled access and multilingual guided tours are also planned.

Above, the Capitoline Museums continue to dazzle with classical bronzes, marble statues, and Renaissance frescoes. But below, a new kind of museum is quietly being built — one where history is quite literally beneath your feet.

“The area has never before been opened to the public as it will be,” D’Ambrosio said.