Original builders of Gaziantep Fortress are not known. The fortress was restored by the Byzantine in the 6th century. The fortress was later saw restoration again in 1481 during the time of Kayitbay, the Egyptian Sultan, and in 1557 during the Ottoman Emperor Suleyman the Magnificent. The fortress was supplemented by watchtowers, mosques and small palaces. There are 36 watchtowers in walls which have a circular shape for 1,200 meters. Mehmet Gazali Tomb, a mosque and a bath exist in the fortress. It is believed there are galleries and paths leading to the river under the fortress. The fortress was an important rampart in resistance against the French during the War of Liberation in 1921.

Gaziantep is the most developed city of GAP in agriculture, industry and commerce. It has its pistachio known by the name of the city. Vineyards and olive orchards are also important. Manufacturing activities in Gaziantep are mainly carried out by small scale enterprises. As a vivacious industrial and commercial center, Gaziantep has cement, textile, leather, shoemaking, soap, woodworks, metal and machinery industries and workshops. It maintains its status as an "export gate" by its 120 different products exported to 40 countries.