For certain values of "mainframe", some are operational or being restored at the Living Computer Museum in Seattle (a very neat place). http://www.livingcomput

For certain values of "mainframe", some are operational or being restored at the Living Computer Museum in Seattle (a very neat place). http://www.livingcomputermuseum.org/The-Collection/Exhibit-Hall.aspx#Mainframe http://www.livingcomputermuseum.org/The-Collection/Exhibit-H...