Here's a thread with a bunch of pictures of Chicago excavations that have exposed vaulted sidewalks http://forum.skyscraperpage.com/showthread.php?t=143407 http

Here's a thread with a bunch of pictures of Chicago excavations that have exposed vaulted sidewalks http://forum.skyscraperpage.com/showthread.php?t=143407 http://forum.skyscraperpage.com/showthread.php?t=143407