You can construct a Treasury in each of your cities.
At level 10 of the Treasury, you can only store one artifact (treasure) & At level 20, you can store two artifacts.
The treasured item will be stored in the Treasury in two ways: Active or Secured. If the Treasure is active in your Treasury, it can be moved by your king to other cities or be pirated by other players. If the treasure is secured in your Treasury, it cannot be moved by you or pirated by other players. The Treasury has 3 additions: Treasures, Transfer Treasure.