Inner Fortification Ring

As early as the 16th century, the plateau of the castle hill was surrounded by a defence wall.

By the end of the 16th century, the entire southern and eastern sides of the castle plateau were enclosed by a defence wall with embrasures. 

Semi-circular watchtowers, called roundels, were located at the corners of this wall. These watchtowers protruded from the wall and served as artillery positions. They were the forerunners of the bastions built later.

A distinctive feature of the inner defence ring is that much of it was built from fired bricks, whereas later structures were made of stone.