In a couple of remote Italian locations, a copy of Leonardo’s secret Codex gets hidden for centuries, until it comes into the possession (around the early 40s) of a certain Government.
Bramante, in his Tempietto, hosted the meetings of the hexagon secret society. He was not in friendly terms with Michelangelo. Other enlightened architects, such as Palladio and Borromini, also initiated to the Society’s secrets thanks to the mysterious symbols left by the clever architect sculpted on the Tempietto, that they both managed to decode, were more fearful about the future – and therefore diligently visited the Tempietto’s cripta and adhered to the Society’s protocol… it all had to do with the hexagon on Saturn’s pole, that also Galileo had seen on Saturn’s pole in his days, but had kept it a secret not wanting to end up burnt at the stake like Giordano Bruno.
Of course, in those days humans didn’t realise one could travel faster than light, be in more places than one at once, allowing them to time-travel. San Pietro in Montorio’s Tempietto was thought to be the place where the Hexagon “Headquarters” could be reached...