They were not called big iron for nothing. They are not measured in racks but metric tons and such :) In 1991, a Hungarian university installed its mainframe by partially removing the roof and craning the thing in place. I am not kidding. Hard to find photos. http://hampage.hu/nosztalgia/netto/ursus/ursus.jpg here's a small section of it.

https://www.backblaze.com/blog/wp-content/uploads/2016/11/hi... look at that dainty hard drive in the back :D