The treasury (or thesauros) in Frourio is a small, temple like structure built to protect the collective wealth of the Citizens and the funds used to operate the city-state. This civic building is operated by the state, rather than families or individuals. As a storehouse for the wealth of the city, it is intentionally designed to be difficult to access or breach. The foundations are tall and without steps, and has very thick walls. The interior has metal gatings and magical defenses to protect the funds from thieves.
The treasury is lavish in structural detail. It has an inner chamber and a front porch or vestibule. It was decorated with sculptures of the learned people of Froúrio and those that had gone on to greatness elsewhere in the islands. The building itself is a source of pride in the city.
The treasury was sacked during the fall of Frourio in 4706. Almost all of the working funds for the city were plundered as part of the Norjord raids. The treasury has been repaired to ensure the soundness of the structure, but has not been completely restored.