Door
From King Arthur's Gold Wiki
Doors are structures/blocks that can be constructed from rock and wood by the builder.
Opens for your team only. Great for locking the sacks in.
It takes 3 wood and 3 rocks to construct.
They are supposed to open automatically for everyone in your team, while staying closed for the opposing team, thereby granting a tactical advantage.
Their main use is to protect your base and the sacks.