Shawn waited for a break in the guide’s description before urging Sana forward to follow the tour group. After ten feet, on their right they came to what the guide had been describing. It was a bluish-white plaster wall with a profusion of incised epigraphs one on top of the other, such that it was difficult to discern any one epigraph in particular. “It’s called the graffiti wall,” Shawn explained in a hushed voice. “As I told you, during the last excavation, in order to get into Peter’s tomb without disturbing anything, in particular this graffiti wall, one had to tunnel under the wall, and then under the wall that supports the original vault over Saint Peter’s tomb. The ossuary is going to be between the two walls, back close to the red wall, which cuts across both at right angles.”

“My goodness,” Sana exclaimed. She shook her head in exasperation. It was too confusing.

“I know,” Shawn said sympathetically. “It’s extremely complex. The site has been added to and altered continuously over almost two thousand years. I might not be explaining it well, but I know what I’m talking about. My only concern is that when the red wall was in the process of being built by the Romans around the turn of the first century, they might have inadvertently stumbled across the ossuary and either moved it or destroyed it. There’s no doubt in my mind that its original location had to have been close to the red wall, which is just behind us.”

“Where does the tunnel start?” Sana questioned as she gazed around the chamber they were in.

“The tunnel is directly below where we are currently standing. At the moment, we are at the level of the floor of Constantine’s basilica. We have to descend to the level of the floor of Peter’s tomb. To get there we have to go into the next chamber. Are you ready to move on?”

“More than ready,” Sana said. Thanks to her discomfort, she wanted to see where they would be working later that night, then leave. Under the circumstances, the three-dimensional details of what Shawn was patiently describing were not registering.

Shawn led the way down a number of metal steps into a relatively large room, where the tour group had reassembled. The guide was explaining that the Plexiglas boxes seen through a small wall opening into Peter’s tomb contained the bones of the saint.

“Is that true?” Sana whispered to Shawn.

“Pope Pius the Twelfth said they were,” Shawn answered softly. “They were found scattered in the tomb within a V-shaped niche in the red wall. I think what swayed the pope was the lack of a skull. Saint Peter’s head historically was supposed to have been in the basilica of San Giovanni in Laterano.”

“Okay, so where is the tunnel?” Sana asked impatiently. She’d had enough history for the moment.