They are slits in the tower and corridor walls. A rectangular one is called "Arrow Sama" .
A circular or triangular one is called "Gun Sama". Even now there are about 400 in the castle.
The geometric pattern of these Sama(slits) is one of the special features of this castle and is
a good material for photographs and pictures.
Photo of various slits on the wall
This gate is situated near Main Tower, and has a basement and two stories.
The basement is a low-ceiling underpass, so the enemy soldiers who pass through are attacked
from the floor of the first story overhead. That means the floor-board can be torn up by soldiers inside.
If the underpass is buried, the iron-covered door is unbreakable. Defensive wisdom is found
in the construction of the gate.
As we approach Main Tower, the gates become narrower, lower and harder to break through.
This Ho Gate is covered with iron and it is so narrow that the enemy soldiers wearing suits of
armor and carrying long spears would not be able to pass through this gate in a group.
Photo of "Ho" Gate
This wall is called "Oil Wall". It is the only one of its kind remaining in the castle.
It is made from sand and clay. They are kneaded with rice glue and the mixture is pressed and hardened.
This wall is like concrete and repels water. Besides, it is bulletproof, so it is still firm after 400 years.
Photo of Oil Wall