The north-east corner round tower of Serdica's fortification system is located on Iskar Street. This archaeological monument includes parts of the eastern and northern fortress walls which are preserved at considerable height. The main stages of construction are well evident: the end of the III century - mixed masonry bricks and stone; the end of the V century - a brick belt.
There are parts of a wall in a state of good preservation which in some places reach a thickness of up to 6 m. In good shape are the stairs on which people had climbed to the tower and to the side exit leading out of the city, as well. The outer diameter of the wall is 22 m and the inner is 4.10 m. There are three rooms for the soldiers in this section of the fortress positioned next to the entrance of the tower. In the XII - XIV century the tower was reconstructed from the outside into a four-sided. Her cylindrical body was covered with a new construction of stone blocks.
Working time: Every day 24 hours open
Entrance: Free
Address: Sofia,1 Iskar Str.
