Fort Thidir is the Stronghold of Zietal Mar, located in the upper holding, and was used as a final line of defence for the Outpost and is a central hub of the Outpost's Government. Its initial construction was commissioned by Marshal Khestor in his first update to the Outpost and work has been ongoing since. With its Chief Architect being Priest Sigmarr, appointed by Khestor as Governor, seasons later.
The original plans for the Fort features extensive amenities, barracks' for The Molir, Offices of the Zietal Mar Government, Bunkers and residences in emergencies, traps, the Zietal Mar Public Bank, the Zietal Mar Public Library, and much more.
Due to the increased assaults on the Outpost, the Fort was never completed.
With the short time to prepare, the Dwarves managed to construct:
- "The Tube", a one-hundred meter spiralling staircase.
- The Government Wing, a corridor for the offices of the Zietal Mar Government.
- The Bunker, complete with security systems and escape routing.
- The 'Anvil Gate' Portcullis, using dropping anvils as a door.
- The 'Airlock' doors, to verify the identity of those wishing to enter, and to trap those unwelcome.
- External Lava pools, to push attackers into.
- Pathway flooding, to slow the progression of attackers.
Fort Thidir saw moderate use while the Island was still regularly occupied, most notably the Jerl Bull assault, the Grol invasion, and the last-stand of Zietal Mar.