Really old, really big, really cool.
Reference:
http://www.luckham.org/LHL.Bell%20Labs%20Days.html
http://www.xmission.com/~legalize/vintage/index.html
http://terminalemulators.net/2010/04/the-ibm-3270-terminal/
http://kludgespot.blogspot.com/2009/12/vintage-computer-ads.html