Juno is an naval fortress originally built in the Dark Ages, but continuously renovated.
During the Middle Ages a navy called the Order of the Seas was established in the naval fortress to deal with piracy in Ordis, which has been known as a prosperous city since antiquity. The Order fought many large-scale naval battles against the pirates near the coast of Ordis.
During the Erebonian Civil War, Juno served as the headquarters of the Noble Alliance. After the Imperial Army of Erebonia and Rufus Albarea of the Noble Alliance concluded on a ceasefire, the Old Noble Alliance spearheaded by General Aurelia Le Guin, commander of the Lamarre Provincial Army, held the castle until August S.1205. Their force at the time consisted of 50,000 soldiers, enormous airships, enough supplies to extend their siege for 3 years and fully equipped antiaircraft artillery. Even the Imperial Army was perplexed on how to deal with the situation.