Michelangelo hid in a secret room under the Medici Chapel in Florence for 3 months during a period of political turmoil, occupying his time by sketching on the walls. His whereabouts were a secret for ~500 years until the museum director stumbled upon the room in 1976. – WTF Fun Facts
Source: https://www.npr.org/sections/parallels/2018/06/03/615181742/this-room-is-thought-to-have-been-michelangelos-secret-hideaway-and-drawing-boar?t=1643625131637
