Other times, it actually takes on solidity and mass in the form of oddly skewed, diagonal slashes of houses. The buildings that fill it look more like scar tissue, bubbling up to cover a void left behind by something else's absence.
News up on the Archimedes Palimpsest, now being exhibited at the Walters Art Museum in Baltimore. [website] [previously]
In the 13th century, thrifty monastic scribes erased an old Archimedes manuscript they had lying around and reused it. Thankfully, they didn't do a very thorough job. Ten years ago today, an anonymous American collector purchased the Archimedes Palimpsest, and has since funded the project to conserve, image, and study the manuscript, which contains several otherwise unknown works. Today, the Archimedes Palimpsest Project has released all its data and images under a Creative Commons license.