Each of the 7 fortresses that guard the border of Keairn from The Wastelands to the north have similar layout. They were built like this to make it easier for the Knights of Eld when they transferred between fortresses. If each fortress is the same, soldiers will never get lost or surprised by anything inside the walls of the fortress.
Red Rock (or Stone Mount, as it was called before the Red Horde captured it) is the exception to the rule. While the general layout is relatively similar to the other fortresses, there are a few minor changes brought about by the fact that it is built into the side of a mountain.
One of the biggest changes is the overall size of the fortress. The other fortresses have large areas dedicated to apartments and rooms that are available for any commoners who might need to take refuge inside the fortress. However, the mountains are sparsely populated, so there are very few rooms available at Red Rock. All of them can be found in the low tower located on the south side of the fortress.
The Fortress itself sits on a wide, natural rock shelf in the side of a mountain. The South and West walls of the fortress butt up against the face of the mountain itself and there is a rocky overhang that extends out from the mountain side and completely covers the fortress from the top. This leaves the East and North sides of the fortress open, allowing for a view of the mountain range and countryside in those directions.