Stephen Wiltshire is an autistic savant artist who can draw entire cities from memory, down the the windows and doors. I saw a video of him drawing Rome from memory on YouTube, then found his web site which has a multitude of videos in various languages.
In his panoramic projects, Stephen is flown over a city via helicopter where he makes his observations without taking a single note or sketch. Then he is given a specified time and space to recreate what he saw from memory. The results are astounding.