Vatican technicians are securing what on Wednesday will arguably become the world's most beautiful bunker, making sure that what happens in the Sistine Chapel stays in the Sistine Chapel.
Michelangelo, meet James Bond.
On Wednesday afternoon, about 133 cardinals under the age of 80 will file into the chapel adorned with frescoes painted by the Renaissance master to enter a secret conclave to decide who will be the next Catholic pope.
They will walk on a newly installed floor elevated to provide a seamless platform with the base of the altar, which is several steps higher than the rest of the chapel.
Just what may be under that temporary floor, apart from wiring for electricity and sound systems, depends on which Vatican official one talks to.
It may, or may not, be the home to jamming devices. The devices may also be near the upper windows of the chapel, which is about 68 feet (20.1 metres) high.
Officials have at times contradicted each other. The details, after all, are supposed to be a secret, maybe even to them. The only thing everyone agrees on is they are there, even if, like the Holy Spirit who is supposed to inspire the cardinals, they cannot be seen.
Other security measures to make sure no one is eavesdropping or trying to get information out reportedly include film on the window to block cameras on drones and special tiles to block signals from cellphones, which are banned anyway.
At the last conclave in 2013, it was widely reported that a Faraday cage had been installed. Such devices can enhance communications security by shielding against electromagnetic fields.
On Monday the office of the governor of Vatican City sent out a laconic note addressed to "Dear Clients" informing them that cellphone towers in the world's smallest sovereign state will be deactivated at 3 p.m. (1300 GMT) on Wednesday and remain off until after the new pope's name is announced.
The 108-acre city-state, however, is surrounded by Rome, and it was not clear if the Vatican was taking any action to block connections to phone towers just outside its walls.
The cardinals will be voting in the chapel up to four times a day. Vatican workers last week hoisted a chimney onto the chapel, which will be used for burning the ballots. Black smoke will tell the outside world no decision has been made, white will announce that the 267th pope has been elected.
PROTECTED 'AT ALL TIMES'
Cardinals will be billeted in the Santa Marta residence, a hotel with about 130 rooms, and an adjacent older residence.
The main Santa Marta residence was cleared of its guests and long-term residents last week so security personnel could electronically sweep the area.
Its main door has been closed, and a sign has been put up telling cardinals to use a side entrance on the left, according to a recent guest who spoke on condition of anonymity.
Wi-Fi signals inside the residence were significantly weaker than normal on Monday, the person said.
Another source, a former Vatican official, said the city-state has its own systems to detect drones and receives regular assistance from Italy.
Vatican gendarmes and plainclothes Swiss Guards will escort buses that will take cardinals between the residence and the chapel. If they wish, the prelates will be allowed to walk the short distance, going around the back of St. Peter's Basilica.
"A protective envelope will be created around the cardinals at all times," one source familiar with some of the security procedures said. "If they do decide to walk in the gardens or take a smoke outside, no one will be able to get close to them."
Aides including priests, cooks, cleaners, drivers and other attendants have already taken an oath "to observe absolute and perpetual secrecy" about whatever they may see or hear.
The penalty for not keeping the secret until death: automatic excommunication from the Church.
