A camera obscura is an optical device that led to photography and the camera. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced, rotated 180 degrees , but with color and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate representation. The largest camera obscura in the world is on Constitution Hill in Aberystwyth, Wales.