Spotted via BLDGBLOG
"Distant changes in air pressure cause the whole system to shudder, whistling subliminally on the edges of the wind, a soundtrack for the city so beautiful it’s often hypnotic. If you wait long enough in certain alleys in Soho, you’ll hear it, droning beneath the rustle of crisp bags and trash. " Urban Knot Theory - BLDGBLOG
Siologen has a gallery of more than 1000 incredible images mapping underground urban geography.