BBC News: X-rays reveal Archimedes secrets.
A series of hidden texts written by the ancient Greek mathematician Archimedes are being revealed by US scientists. Until now, the pages have remained obscured by paintings and texts laid down on top of the original writings. Using a non-destructive technique known as X-ray fluorescence, the researchers are able to peer through these later additions to read the underlying text. The goatskin parchment records key details of Archimedes work, considered the foundation of modern mathematics. The writings include the only Greek version of On Floating Bodies known to exist, and the only surviving ancient copies of The Method of Mechanical Theorems and the Stomachion. In the treatises, the 3rd Century mathematician develops numerical descriptions of the real world.
Archimedes' writings were transcribed in the 10th century onto parchment. Three centuries later, the parchment was scraped and recycled, and Greek Orthodox prayers were written on the pages. In the 20th century, forgers added gold paintings to the pages. But the original work is still there, so long as you have a synchrotron handy. Take a look at the Archimedes Palimpsest.