What is the benefit of "claiming" a Fort or other location for your guild?

Like, does the guild get a collective character buff or ...something? Is it just to look pretty?

Solution 1:

Claiming keeps and other ressources has advantages:

• Your guild store will be accessible to all alliance members inside the keep (they can't sell things, but they're able to buy off your guild's supply).
• You're able to upgrade/improve the keep or ressource, e.g. making the guards more powerful, adding new guards, etc.
• It's some kind of status symbol as well even if this point doesn't have any direct gameplay impact.
• In DAoC you typically got warnings to guild chat when/if guards of your keep died. I don't think this is in the game yet, but I could imagine them adding stuff like this later as well (unless it's in there already, didn't claim anything so far).

Solution 2:

I can't speak from experience, however from what I've been able to judge from various discussions between other players, the fort seems to allow trading within your guild's "Alliance". This probably means its for larger, more established guilds to interact with other larger guilds.