Small Stone Keep

Must be placed using the House Placement Tool
Footprint: 24 x 24
Stories: 2
Rooms: 10 (plus 4 small balconies)
Lockdowns: 2625
Approx. Price: 562,752

With the following publishes, more keep designs became available:
Publish 101
Publish 103
Publish 105
Publish 107

The price for customization varies between 20,000,000 and 28,000,000 gold coins.

The safest method to customize an existing keep is by first removing any masonry walls and tiles, as well as any gozas and add-ons. Else these may disappear under the house's foundation, making them impossible to retrieve. Other objects will be packed into the moving crate.

Double-click the house sign and select Customization. If the building is properly placed and if the option to convert it to a new design isn't greyed out, you can go ahead.

If the option called "convert into customized house" is not available, try to choose "Securely replace This House".

You will get a "confirmation question" before the options menu.

Now you can choose between different styles if you are rich enough.