The shape he was looking at was not intended as a diamond at all. The four points only formed a diamond because Langdon had connected adjacent points. The Illuminati believe in opposites! Connecting opposite vertices with his pen, Langdon’s fingers were trembling. There before him on the map was a giant cruciform. It’s a cross! The four elements of science unfolded before his eyes… sprawled across Rome in an enormous, city-wide cross.

As he stared in wonder, a line of poetry rang in his mind… like an old friend with a new face.

’Cross Rome the mystic elements unfold…

’Cross Rome…

The fog began to clear. Langdon saw that the answer had been in front of him all night! The Illuminati poem had been telling him how the altars were laid out. A cross!

’Cross Rome the mystic elements unfold!

It was cunning wordplay. Langdon had originally read the word’Cross as an abbreviation of Across. He assumed it was poetic license intended to retain the meter of the poem. But it was so much more than that! Another hidden clue.

The cruciform on the map, Langdon realized, was the ultimate Illuminati duality. It was a religious symbol formed by elements of science. Galileo’s path of Illumination was a tribute to both science and God!

The rest of the puzzle fell into place almost immediately.

Piazza Navona.

Dead center of Piazza Navona, outside the church of St. Agnes in Agony, Bernini had forged one of his most celebrated sculptures. Everyone who came to Rome went to see it.

The Fountain of the Four Rivers!

A flawless tribute to water, Bernini’s Fountain of the Four Rivers glorified the four major rivers of the Old World—The Nile, Ganges, Danube, and Rio Plata.

Water, Langdon thought. The final marker. It was perfect.

And even more perfect, Langdon realized, the cherry on the cake, was that high atop Bernini’s fountain stood a towering obelisk.

Leaving confused firemen in his wake, Langdon ran across the church in the direction of Olivetti’s lifeless body.

10:31 P.M., he thought. Plenty of time. It was the first instant all day that Langdon felt ahead of the game.

Kneeling beside Olivetti, out of sight behind some pews, Langdon discreetly took possession of the commander’s semiautomatic and walkie-talkie. Langdon knew he would call for help, but this was not the place to do it. The final altar of science needed to remain a secret for now. The media and fire department racing with sirens blaring to Piazza Navona would be no help at all.

Without a word, Langdon slipped out the door and skirted the press, who were now entering the church in droves. He crossed Piazza Barberini. In the shadows he turned on the walkie-talkie. He tried to hail Vatican City but heard nothing but static. He was either out of range or the transmitter needed some kind of authorization code. Langdon adjusted the complex dials and buttons to no avail. Abruptly, he realized his plan to get help was not going to work. He spun, looking for a pay phone. None. Vatican circuits were jammed anyway.

He was alone.

Feeling his initial surge of confidence decay, Langdon stood a moment and took stock of his pitiful state—covered in bone dust, cut, deliriously exhausted, and hungry.

Langdon glanced back at the church. Smoke spiraled over the cupola, lit by the media lights and fire trucks. He wondered if he should go back and get help. Instinct warned him however that extra help, especially untrained help, would be nothing but a liability. If the Hassassin sees us coming… He thought of Vittoria and knew this would be his final chance to face her captor.

Piazza Navona, he thought, knowing he could get there in plenty of time and stake it out. He scanned the area for a taxi, but the streets were almost entirely deserted. Even the taxi drivers, it seemed, had dropped everything to find a television. Piazza Navona was only about a mile away, but Langdon had no intention of wasting precious energy on foot. He glanced back at the church, wondering if he could borrow a vehicle from someone.

A fire truck? A press van? Be serious.

Sensing options and minutes slipping away, Langdon made his decision. Pulling the gun from his pocket, he committed an act so out of character that he suspected his soul must now be possessed. Running over to a lone Citroën sedan idling at a stoplight, Langdon pointed the weapon through the driver’s open window. "Fuori!" he yelled.

The trembling man got out.

Langdon jumped behind the wheel and hit the gas.

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