October, 1529: troops of the Holy Roman Empire laid siege to Florence, Italy. A committee called the “Nine of the Militias” was appointed to construct defences for the city, and one of the nine was Michelangelo Buonarroti. Michelangelo was ultimately made “governor and general prosecutor of fortifications”.
Due to treachery on one hand and the sudden illness of Francesco Ferruccio on the other, Florence ultimately fell in the summer of 1530. The victors began to enact their revenge upon the defenders and Michelangelo went into hiding in a small corridor underneath the New Sacristy of the Basilica of San Lorenzo, where he had been working on Medici tombs.
Faced with three months of solitary confinement surrounded by four blank walls, what else would Michelangelo have done? The corridor was not discovered until almost 450 years later, in 1977, and is not open to the public.