Michelangelo painted the Sistine Chapel on his feet, not lying down

Popular culture depicts Michelangelo lying on scaffolding to paint the Sistine Chapel ceiling. He was actually standing upright, arching backward with his arms raised above his head — a posture he described as torturous in letters to his father. He wrote that the paint dripped in his eyes and that his neck hurt for months after finishing. The ceiling covers 500 square metres and was painted in roughly four years (1508–1512) using the buon fresco technique, which requires painting on freshly laid wet plaster before it dries. Sections that dried before completion had to be cut away and replastered.

Source: King, Michelangelo and the Pope's Ceiling (2003)