of Soltan Abad had a thick wall surrounded by 7-meter-deep moats. Eight towers were constructed around the town and the governmental building was established in its northern part. In 1891, shops, gardens, and government buildings of Soltan Abad were repaired by the order of deputy governor Mirza Hasan (Etemad os-Saltane). Large parts of the city were formerly annexed as personal property to the pre-existing army commanders, and were then ultimately turned over to the state around 1918–1922. Beginning by the last quarter of the 19th century, the city achieved major developments in carpet industry, and eventually became Iran's most important center of carpet production for export markets, continuing up until at least 1940. Under the reign of Reza Shah of the Pahlavi dynasty, the city was renamed Arak. Modern factories for vegetable oil, soap, sugar beet, and wool industries were established within the city. Arak also became an important station for the Trans-Iranian Railway, a major railway project directed by Reza Shah which was completed in 1938. In 1972, two major state-owned enterprises were established in the city, including an aluminum smelter and a heavy engineering plant. The aluminum smelter was built under the Regional Cooperation for Development project of the Central Treaty Organization, in cooperation with the company of Reynolds and Reynolds. The engineering plant was processed with equipment and technical advice from the Soviets, in return of gas sales to the Soviet Union. The city officially became a metropolis on April 6, 2013, after the merger with Karahrud and Senjan. In 2017 a man shot dead seven members of his wife's family in a mass shooting and attempted murder–suicide. Geography Arak is surrounded by mountains in the south, west, and east, and its average altitude is about 1750m above sea level. It is located 260 km from the city of Tehran, and is in the vicinity of the cities of Qom and Isfahan. Climate Arak has a hot-summer mediterranean continental climate (Köppen: Dsa, Trewartha: Dc), that is, in general, relatively cold and dry. The weather of the city is hot and dry in summer, windy and cool in autumn, cold and snowy in winter, and mild in spring. Its maximum temperature may raise up to 35 degrees Celsius in summer and fall to below -25 degrees Celsius in winter. The average rainfall is around 350mm and the annual relative humidity is 46%. Transport Airport Arak is served by