Stephen Wiltshire is drawing a 20-foot-long panorama of New York City’s skyline based on the photographic memory he has with him after a short helicopter ride.

The London-born Wiltshire, who was diagnosed with severe autism when he was 3, can reproduce the specific details down to the number of windows on a building.

His New York City panorama, which will be his largest to-date, will serve as the finale to his collection of nine of the world’s best-known cities, which includes London, Tokyo, Hong Kong, Rome, Madrid, Frankfurt, Dubai and Jerusalem.