Stronghold

The Stronghold is a the primary structure of your Base.  Its level determines the level to which you may level up all other buildings.

It may be upgraded to a maximum of level 23 and gains additional space in which to build, along with the corresponding possible buildings to fill those spaces, at the following levels:

Stronghold Upgrade Space

Level	New Buildings
3	Farm, Mine, Food Storage, Forge
5	Farm, Iron Storage, House, Training Camp
8	Farm, Mine, Iron Storage, Forge
10	Unlock Barracks*
11	Farm, Food Storage, House, Training Camp
15	Farm, Mine, Iron Storage, Forge
20	Farm, Food Storage, House, Training Camp
21	Unlock Hunter's Lodge and Advanced Buildings**
22	Allows to convert second advanced budilings.***
23	Unlocks Alchemy Lab****

• Stronghold Level 10:  Barracks, Hunter's Lodge, and buildings labeled 'Advanced' are each Advanced Buildings.  These buildings Convert already-leveled buildings into the Advanced one.  See each individual page for more information on its own requirements for Conversion.  Because of said conversion, no new building slots are acquired at SH level 10 or 21.

• Stronghold Level 21:  Unlocks the following Advanced Buildings: Advanced Farm, Advanced Mine, Advanced Food Storage, Advanced Iron Storage, Advanced House and Hunter's Lodge, which can be further upgraded to level 10.
• Stronghold Level 22: Allows to convert second advanced buildings.
• Stronghold Level 23: Unlocks Alchemy Lab.

Upgrade Costs

Level	Iron Cost	Time
2	4,900	1m
3	12,300	10m
4	26,500	55m
5	47,700	2h 15m
6	75,600	4h 25m
7	113,000	7h 35m
8	162,000	11h 45m
9	228,000	17h 5m
10	301,000	23h 35m
11	388,000	1d 7h
12	489,000	1d 17h
13	619,000	2d 3h
14	753,000	2d 15h
15	903,000	3d 4h
16	1,073,000	3d 19h
17	1,260,000	4d 12h
18	1,490,000	5d 6h
19	1,729,000	6d 2h
20	1,969,000	7d
21	2,108,000	8d 1h
22	2,367,000	9d 4h
23	2,439,000	10d 9h