The Sistine Chapel is 40.9 metres (134 feet) in length and 14 metres (46 feet) in width. It has a height of 12 metres (39 feet). The chapel was originally painted in 1512 by Michelangelo for the Pope's use during church services. He decorated it with scenes taken from the Book of Genesis, including the creation of Adam and Eve, and the stories of Noah and Abraham. Michelangelo designed the chapel to be lit by natural light coming in through large windows on the north and east walls. He also included some small windows of his own design on the south wall, which let in some sunlight but not much. In addition, there are small windows along the base of the walls where paintings would have been mounted. The artist planned to decorate the walls with paintings based on episodes from the Old Testament, but he died before finishing them. So, after his death, his friends and assistants continued to work on the chapel. The last major work done on the chapel was the altar piece by Borromini. He designed the marble altar in 1640-1650. The altar was never used because the Pope who commissioned it died before it could be installed.