Monte Rosa could be seen from many places on the south side of the Alps and it had been mentioned in many travel diaries. At the end of the 15th century some outlines of the mountain may possibly have been painted by Leonardo da Vinci into the background of the Madonna of the Rocks or other pictures. Da Vinci explored the Italian side of the mountain and made some observations, though there is but scanty evidence that he had climbed even a minor summit in the neighbourhood. He was intrigued by the permanent snow lying on the mountain and the darkness of the sky above him, he wrote: