Here’s another large round door, this time an Emil Strauss design built by Mosler in the Chicago Board of Trade building:
Though I haven’t confirmed it’s a Mosler based on anything concrete, it does closely match other doors that are Mosler. Note there are roller bearings to support some (but not all) bolts to keep friction and wear under control.
The building was constructed 1929-1930 and is a fine example of Art Deco, probably hit by the Great Depression during construction.
Building references:[INDENT]http://en.wikipedia.org/wiki/Chicago_Board_of_Trade_Building
http://www.emporis.com/building/chicagoboardoftrade-chicago-il-usa
http://www.cbotbuilding.com/[/INDENT]
Normally the basement is off limits to visitors but there was a “special viewing” of sorts in 2013 and most available imagery is from the weekend of October 19/20:[INDENT]http://www.flickr.com/photos/kramerdesignstudio/10392134665
http://www.chicagonow.com/another-look-chicago/2013/10/first-time-in-83-years-the-board-of-trade-opens-vault-to-public-photos/#image/1
http://www.flickr.com/photos/balinesecat/12215922484 (source of above image)
http://www.demotix.com/news/3019275/chicago-board-trade-opens-vault-public-first-83-years/all-media[/INDENT]
That last URL points out that for a time after the vault was no longer used as a vault, it was a coat room. There is also an image of the blueprint for this area showing a second door (shown in an image as well, rectangular) and a second “Trunk Storage Vault” shares one wall but the other walls are thinner as is the single door, but no images have been found yet.
