Spread across hundreds of square metres at the top of the Palazzo San Carlo and boasting a huge terrace with magnificent views over Rome, Bertone's sumptuous retirement pad has became synonymous with the kind of clerical extravagance Pope Francis has vowed to stamp out.
Now it is set to cause further embarrassment to the famously frugal pontiff after it was confirmed that a probe has been launched into how €200,000 worth of the renovation costs came to be paid by a Foundation linked to Rome's Bambino Gesu (Baby Jesus) children's hospital, which is run by the Vatican.
Bertone himself is not under investigation but officials are examining the conduct of the hospital's former chairman, Giuseppe Profiti, and its former finance chief, Massimo Spina, a Vatican spokesman said.
The probe follows revelations by investigative journalist Emiliano Fittipaldi, who is one of two reporters currently on trial in a Vatican court for obtaining classified documents which provide evidence of waste, irregularities and extravagance in the Holy See's finances.
The controversial trial is currently suspended due to the ill health of one of the three Vatican officials charged alongside the journalists.
Press freedom bodies have attacked the Vatican for prosecuting journalists whose revelations have been shown to have been in the interest of the Church and its followers.
Earlier this year, Francis announced new rules for the naming of saints after Fittipaldi and his co-accused Gianluigi Nuzzi revealed how the current system could be abused to generate large profits for private companies connected to the Vatican.
The books also highlight how flats like the one occupied by Bertone are frequently let out at peppercorn rents with no system in place to decide on what basis they should be allocated.
The cardinal's apartment is frequently described as being nearly 700 square metres (7,500 square feet) in size. He insists it is less than half that and has stressed that he shares it with the three nuns who look after him and his private secretary.