Ancient Gabala castle walls - Gabala was the first capital city of Albania; it played an important role in the economical, political and cultural life of the country since IV century BC; it was mentioned in written sources starting from the first century of our era. Approximately 2500 years old ancient Gabala town which had been capital city of Caucasian Albania for nine centuries was one of political-economical and trading centers of the world and could be compared with such ancient and famous cities as Babylon, Troy and Pompey. Remainders of big buildings, castle walls and monuments of material culture prove Gabala being a grandiose ancient city. Gabala’s grandiose castle walls differ from the defense system of the other Middle Age cities of Azerbaijan. The walls of Selbir have been constructed from air-brick and polished river stone what is especially characteristic for the architecture of Sasanid period. Semicircus form tower have been built from clay mud and the mixture of air-brick and chaff. Diameter of the inside part of the tower is 3 meters. Air-brick mask had been applied to the outside tower and walls. There are remainders of supporting inside wall built with river stone, burnt brick and white-lime solution. According to the investigators’ opinion, this 6 m length wall has been built after the walls with the restoration purpose. There is one more right-angled form tower with 14 m height. It had been built with white-lime and polished river stone, and tuff stone mask had been applied later. In opinion of the specialists, this tower built in I century BC has served as a reliable defense system of the city for centuries. Remainders of a 35 m height, 1 meter thick and 2.4 m length wall have been found in the north side from this above mentioned tower. This wall has been constructed from polished tuff stone and white-lime. The defense walls of the castle part attract the attention with its grand. South walls which have kept its primary appearance up to this day are especially magnificent. The main door is located on the south. It is possible to say that giant towers had been built in right and left side of the castle door remained safe. The walls’ foundation had been constructed with big polished tuff stones in four-cornered form and the upper part was constructed with different sized burnt bricks. There were 15 kinds of bricks used in the construction that differ in size. It is interesting that the masters skillfully used different sized bricks in the construction and created a rare architecture example. Four towers remained in the south wall of the Castle. They all are in semi circus form. The castle tower wall’s height is 10-14 m, diameter of walls is 6-8 m, thickness is approximately 4 meters; towers’ walls have been constructed with about 70 rows of brick.