I heard the story on NPR.
The crazy things one finds when one remodels one's home. I must say this one would have pleased me more than the 3" thick slab of concrete covering the floor above my bathroom in my 100 y.o. Arts & Crafts house. (If anyone knows why such a slab would have been put in, probably over 50 years ago, on a second story floor, fitting the exact dimensions of the bathroom below, please let me know. We're still baffled by that one.) Give me Superman comic in the walls any day!