Hassanabad Fortress, which is located 5 kilometers outside of Sanandaj, is a Parthian (247 BC–224 CE) and Sassanid (226-651 CE) structure. It is believed that this fortress was the center of command and an important Persian stronghold during the Roman-Persian wars (92 BC – 629 CE). The walls of this fortress of 1,100 meters long and reach a height of 200 meters in some parts. The fortress has stone watchtowers. In the 17th century when the Ardalan Vassals ruled in Kurdistan, parts of this fortress were destroyed in accordance with a treaty signed with Shah Safi (1611 –1642). A 3,000-year-old cemetery has been found in the vicinity of the fortress which yielded pots filled with bronze. The fortress is a registered National Heritage Site.