Michelangelo painted the ceiling in a style called fresco, where artists apply colour to wet plaster so the pigment soaks in and lasts for hundreds of years. The ceiling is about 40 metres long and 14 metres wide - imagine laying seven double-decker buses end to end. It shows more than 300 figures in vivid colours that still look bright today, over 500 years later.
Michelangelo was 33 years old when he started painting the ceiling. He built a special curved scaffold so he and his assistants could reach the ceiling without hurting the floor below. He worked in sections, starting at the entrance end. Each section had to be finished before the plaster dried - usually within a day - so the paint would bond permanently to the wall.
According to his letters, the work was incredibly uncomfortable. He had to keep his neck bent back and his arms raised for hours at a time, and paint kept falling into his eyes. By the end of four years his neck and eyes hurt so much that he said he could only read letters by holding them above his head. Even so, the finished ceiling is considered one of the greatest artworks ever made.