The Archeological Crypt of the Île de la Cité (Crypte Archéologique de L'île de la Cité) offers different itineraries to see ruins including 3rd-century homes, a 4th-century bathhouse, and the ancient port on the River Seine, as well as the remains of a two-story, 12th-century home, an 18th-century hospital, and shops built along the rue Neuve-Notre-Dame in the second half of the 12th century. With a Paris Museum Pass or a hop-on, hop-off bus tour that includes entry to the site, you can skip the line for tickets.
The Archeological Crypt is beneath the square in front of the Cathedral of Notre Dame, and is accessible via metro line 4 (Cité ou Saint-Michel stop), the RER train (Saint-Michel Notre-Dame stop), or a number of city bus lines.
The archaeological site is open Tuesday–Sunday (with closures on a few holidays), and can be visited in less than an hour, offering a nice break from the crowds and heat on street level during the summer months. Pair your visit with a tour of the top sights on Île de la Cité, including the Cathedral of Notre Dame and Pont Neuf.
The Notre Dame Cathedral (Cathédrale de Notre Dame de Paris), a masterpiece of medieval architecture, has long been one of the top sights in the city. As a massive restoration is still underway following the 2019 fire, it's scheduled to reopen in December 2024. The cathedral square and the crypt are open to visitors.
