the Detailed Introduction about the Archeage Castle

Castles are a large, end-game structure that are only feasibly constructed and controlled by a guild. They can only be built on Auroria. They are modular, allowing you to create your own castle with a unique layout and they also introduce a new method for PvP with Castle Sieges. This guide about Castles:

Benefits
Castles help to protect the activated Guard Tower you build the castle around. This guard tower is what gives you control over the surrounding area. When activated, the sword will float in the air, and it is possible to destroy the stone and take control of the land if it is not protected.

Controlling this territory opens up new places to build houses and farms. On a crowded server, these may be the only places left to build.

Owning this territory means that you collect all of the taxes of properties that are placed on your land (and you can control who builds on your land as well). Keep in mind, no matter who places the castle and activates the Guard Tower, the guild leader is the one who owns that land.

You also get access to some resources that will be much easier for you to collect than others trying to invade your space.

If you want a castle, then how to activate the stone and build the structure?

First, you need to activate the Guard Tower. This requires crafting Purifying Archeum. This is an item made with the alchemy skill and takes 50 x Delphinad Ingots and 50 x Blood Archeum Crystal. This counts as a trade pack. With this on your back, you are able to activate a guard tower, meaning that you and your guild now control the territory surrounding the Guard Tower.

However, this tower is unprotected, meaning a rival guild may try to take control by besieging your land; a task made quite easy if you have no defenses.

So now you need to build walls, towers, gates, and ladders. First, you need to purchase the various items on Mirage Island. They cost Gilda Stars(Currently the costs have become Gold after the 1.2 Patch), or you could check the Auction House to see if anyone is selling them. With these, you can place the various components into whatever shape and size you wish. Each of these pieces will cost quite a bit of lumber and wood to construct, it is helpful to set up crafting benches so that you don't have to bring the stone and lumber trade packs long distances overseas.

Types
As with all buildings, there is an East and West style to both castles. They look different but have the same function.

Sieges
Once a week on Saturdays, Guilds are able to besiege your castle in an attempt to take control. In order to attack your castle, guilds must bid on the right to attack. The guild with the highest bid gets the right to attack your castle. These battles are 70 v 70 at the max for guild members. However, the defending guild is able to bring in 30 other players as mercenaries, and the attacking guild is able to bring in another 30 members to match, making the largest possible total 100 v 100. The main goal of the attackers is to breach the walls and destroy the Guard Tower inside.

Defenders on the walls can activate fixed cannons using a Blood Archeum Crystal while the attackers can bring Siege Weapons to try and destroy the castle walls or scale the castle walls. In the end, victory for the attackers means that they now control the Guard Tower and surrounding land, while victory for the defenders means they get a special form of currency, Coins of the Lord.