Stereogram, the Trocadéro Palace

A stereogram depicting the main pavilion of the 1878 Paris Exposition, the Trocadéro Palace. When viewed with a stereoscope, the two identical images side by side form a three-dimensional image. The backing paper of the photo, printed on thin paper, is painted with watercolours. This makes the same photo appear to be taken at nighttime when it is viewed against the light.