If you haven’t read about Project Babylon: Gerald Bull’s Downfall, it’s quite fascinating:
His success on the G5 won the attention of both Iraq and China. He built and sold advanced artillery to both nations through an Austrian outfit throughout the 1980s. Having developed something of a personal rapport with Iraqi dictator Saddam Hussein, Bull finally saw an opportunity to realize his ultimate goal. He convinced Hussein that, like Israel, Iraq needed the ability to launch satellites into orbit if it were ever to become a true regional power.
Work began on Project Babylon with a prototype of the supergun in the mid-1980s. This gun, named Baby Babylon, had a bore diameter of about 1 foot, and was approximately 100 feet long. It was mounted horizontally for test purposes, and was believed to have been constructed solely to develop the technology needed for Big Babylon. Nevertheless, Baby Babylon would have had a range of over 400 miles if properly mounted.
The appropriately named Big Babylon was so large that it had to be dug into a hillside for support. Its bore was 3 feet in diameter, and was over 500 feet long. Once completed it would have been capable of launching over 2 tons into orbit — about the size of a small reconnaissance satellite.