Project Babylon. The last supergun project in recent memory. Project Babylon was a fixed artillery piece meant to launch projectiles at least 1000km, when completed the gun would have had a bore of a 100cm (surpassing Little David and Mallet's Mortar at both tied at 91.4cm as ths largest artillery piece ever built). Saddam would have easily been able to reach all of Israel and a pretty good chunk of Iran. Project Babylon was abandoned when the designer, Gerald Bull, was assassinated, and most of the components were confiscated in Europe.
The one problem with this idea, was that it was stationary, and extremely vulnerable to air attack, similar to the German supergun, the V-3. However, simply having the capability to reach out and touch your opponent 1000km away, faster than with a missile, gives you the ability to threaten other countries with it. Either way this was an ill-conceived idea and was a drain on Saddam's resources, with little military value.