Stronghold One was a fortress located underground. It was built on the planet of Makeb within a volcanic mesa. It was constructed to house the planet's treasury during Makeb's initial mining boom. This fortress was submerged in a pool of lava, having only one access point at the surface, and six distinct defensive layers. In the time of the Conquest of Makeb, the InterStellar Regulators handed the treasury over to the Hutt Cartel. The Hutt Cartel then used the vaults to store their isotope-5 reserves. Szajin commanded scientists who engineered and assembled isotope-5 droids within the confines of Stronghold One. The Sith Empire launched a raid on this facility, hoping to pilfer the isotope-5 reserves, but instead, they encountered the Hutt's army of isotope-5 droids.