Science and art. Two subjects I struggled with at school but put them together and hot damn I love what you get. Such as this news story, and the paper published by the scientists involved.
Scientists Joris Dik and Koen Janssens used high-intensity X-rays from a particle accelerator to scan the painting and reveal the face beneath. The powerful X-ray bombardment caused atoms in the picture's layers of paint to emit "fluorescent" X-rays of their own, which indicated the chemicals they originated from. That enabled a colour map of the hidden picture to be produced.
Now, how cool is that?