According to a classic Joni Mitchell song, “They paved paradise and put up a parking lot.” But in Paris, ironically, it was the building of a parking lot that unearthed a wealth of archaeological treasures, including some that date back to the Gallo-Roman era that began in the year 52 B.C.

And even more surprising is that this historical treasure trove literally lies at the feet of every tourist who visits one of Paris’s iconic sites—Notre Dame cathedral.

Now a museum called the “Crypte Archeologique,” the site was uncovered by workers constructing an underground parking lot adjacent to the cathedral in the 1960s, leading to an excavation underneath the plaza in front of the iconic church between 1965 and 1972.

Among the discoveries:

• A section of a river wall dating to the ancient port of Lutetia, a Roman city founded on the Ile de la Cite in the 1^st century B.C., which is the predecessor of present-day Paris;
• A public bath from the Gallo-Roman period;
• Part of a protective wall that encircled the Ile de la Cite, dating from the 4^th century;
• A section of the former chapel of the Hotel-Dieu, dating to the 7^th century;
• The foundations of several houses that lined the Rue Neuve-Notre Dame, dating back to Middle Ages;
• The foundation of the Hospice des Enfants-Trouves, a religious charity aiding poor, orphaned and abandoned children, built in 1638;
• And sections of the original Haussmann sewers, constructed in the 1850s.

The entire site is now one of Paris’s 14 city-run museums and is open from 10 a.m.-6 p.m. (last admission at 5:30 p.m.) Tuesday-Sunday, closed Mondays. Of note, while the other city museums are free to enter, the Crypte Archeologique charges an admission fee of 8 euros for adults (those under age 18, the disabled and senior citizens are admitted free of charge).

It’s also important to note that it’s entirely possible to miss the entrance to the museum at the far end of the Place Notre-Dame/Place Jean-Paul II due to abysmally inadequate signage. Look for the ramp to the underground parking garage that is sandwiched between the Rue de la Cite and the short street Parvis Notre-Dame. The entrance to the museum, marked by a concrete sign with red lettering, is just on the other side of the parking ramp as you make your way toward the cathedral.

The underground museum is divided into 10 sections:

• 1) The Parisii, the residents of the Ile de la Cite before conquest by the Romans;
• The Rampart;
• 3) Lutece at the height of the Roman Empire
• 4) The Ancient Port
• 5) The Medieval Cave
• 6) The Construction of Notre Dame
• 7) The 17^th Century
• 8) Hospice des Enfants-Trouves
• 9) Napoleon III and Haussmann
• 10) The Ancient Baths

There’s an audio tour—lasting about 30 minutes—available in several languages to guide visitors through the various sections.

We’ll be honest here, though: The vast majority of City of Light tourists don’t visit the crypt as they have no real interest in the archaeological digs. Sure, the museum is unusual and can easily be explored in under a half hour.

But unless you’re a history buff or a regular visitor to Paris looking for new experiences in the city, the Crypte Archeologique isn’t a must-see destination.

However, if you are into archaeology or want a deeper understand of Paris’s rich 2,000-year-plus history, the museum is certainly worthy of a quick visit.