A pair of researchers at the University of Granada has solved the mystery of the purple stains on the ceilings of the famous Alhambra palace in Spain. In their paper published in the journal Science Advances, Carolina Cardell and Isabel Guerra describe their study of the ceiling of the famous medieval fortress and what they learned about its mysterious purple stains.
Click here for original story, Electron microscopy reveals the reason for the purple stains on Alhambra ceilings
Source: Phys.org