Art Under the Microscope: Threads. The Getty, 2016
This post by the The Getty sucked me in for at least an hour. It's a photo taken with a microscope of the background threads in the tapestry Triumph of Bacchus (1518-1520). You can see not only how the piece was woven, but how the threads were spun. I can't stop looking at it.
Conservators use this type of photography to help preserve art.