Operating out of an underground research laboratory and fabrication facility on the moon of New Sparta in the Hadrian system, Project Bolo designed and constructed several prototype Mobile Siege Fortresses, enormous ground-combat vehicles the size and shape of ancient Egyptian pyramids.
The original idea was to provide a safer and less manpower-intensive way to take control of the surface of Bug-infested worlds, so that more troops could be sent actually into the underground Bug tunnels to flush them out of their hives. Surface combat against the massive wave attacks that the Bugs favored required enormous amounts of firepower and reserves of ammunition, a combination that normally would call for extensive field fortifications. But field fortifications are worse than useless against an enemy who can tunnel through rock and soil almost as easy as a man can swim through water, and wheeled or tracked vehicles are not much better against an enemy who can come at you from below.
So these Mobile Siege Fortresses, despite their great size, were designed to hover several meters above the ground using Antigrav equipment, and even their undersides are extensively armored and bristling with anti-personnel weaponry. Their upper surfaces are similarly armored, and bristling not only with anti-personnel and anti-vehicle weaponry, but even beam and missile weaponry capable of reaching high into orbit above a planet, to provide a mobile defense platform agaisnt enemy ships in orbit.
Both sponsoring governments were eager for a new weapon against the Bugs, as well as one that could be used against the Jurvain. The Colonial Marines of the Frontier Worlds Territory especially wanted something to supplment their meager manpower reserves, while the Earth Federation, then going through the 3rd Civil War, wanted some way to allow Light Infantry forces to engage the Tech Infantry Rebels on a more even footing. However, the project came to an abrupt halt when Andrea Treschi stole the testing data and blueprints, then had the facitly attacked and destroyed from orbit by Horadrim warships operated by Internal Security, for reasons never adequately explained.
The amusement park of Sylvania was later built on the ruins of the laboratory and fabrication facility by eccentric billionaire Izzy D'Argent.