To prevent issues when players wish to claim a standard Fortress, desert temple, stronghold, ocean monument, or nether fortress the following guidelines will apply:
Claiming of Fortresses:
The 20 block build rule still applies to Fortresses.
Can not be claimed by simply placing a sign saying you own it.
Can not be claimed by destroying all the blocks and rebuilding them so you "own" the blocks.
Can be claimed with a Faction.
Can be claimed with purchased WorldGuard regions.
Can be claimed by building doors, signs, chests, and other items that clearly show a player is building in that area. (The area must look significantly different from a natural structure in order to avoid confusion.)
You may destroy blocks in a Fortress only if you know 100% that it is not claimed by another player (if you don't know ask a staff member).
If you ever have any questions about any of these Rules please ask a staff member.
How do you know if a Fortress is claimed or not claimed?
It is your responsibility to investigate the area surrounding the Fortress and look for any sign that it is already claimed by another player. If you are still unsure after looking around then you should ask a staff member to check the area and see if it appears to be claimed by someone.