.
One of my favourite paintings, Vermeer’s Girl Reading A Letter at an Open Window, has been revealed to be something other than what we have all grown to know.
Recent restoration has shown that the blank white wall in the background originally contained a large picture of Cupid, probably indicating that the letter in question was a love missive.

“Behind [the girl] there was an empty white wall. But in 2017, we started with a big restoration and research project to do the restoration of the painting,” Uta Neidhardt, senior curator at Gemäldegalerie Alte Meister (Old Masters Picture Gallery) in Dresden, Germany.
Laboratory tests indicate the overpainting was done about 70 years after the painting was completed, and after Vermeer’s death in 1675. One theory is that the picture had been attributed to Rembrandt and the cupid was removed as it was not a detail usually associated with Rembrandt; the alteration thus added to the valuable — but wrong — attribution when the painting was presented to a Saxon prince in the 1740s.