Archaeologists working to restore Paris’s fire-damaged Notre Dame cathedral have discovered something remarkable: previously unknown tombs hidden beneath the 850-year-old Gothic church. Workers made the discovery while installing ground-level scaffolding to help rebuild the church’s fallen spire, according to a statement from the French Ministry of Culture. When they realized that there was something buried at the spot where the transept crosses the nave, the cathedral called in the Institute for Preventive Archaeological Research to investigate. What they found were several tombs and a leaden sarcophagus, probably dating to the 14th century. “The floor of the transept crossing has revealed...