First unleashed by the Terran Hegemony in 2460, the Helepolis is a ponderous BattleMech designed to deliver artillery fire. The 'Mech was proven ineffective on multiple occasions and, following the destruction of the production facilities in 2775, the design was lost during the Succession Wars. The HEP-2H dates to 2488.
The Helepolis is a slow heavy 'Mech with a maximum speed of 54 km/h. It has a respectable thirteen tons of armor, however.
When rebels within the Hegemony military launched the September Revolt, the new Director-General, Ian Camerondeployed batteries of Helepolis 'Mechs to keep them pinned down within the capital city of Geneva at Terra. [Source: sarna]
You can download the papercraft model here: Classic BattleTech - Helepolis Free Mech Paper Model Download