Damghan is situated 342 kilometres (213 mi) east of Tehran on the high-road to Mashad, at an elevation of 1,250 m (4,101 ft). The city trades in pistachios and paperalmonds (kaghazi), with very thin shells, which are famous throughout the country.
Damghan was an important city in the Middle Ages, and was the capital of the province of Qumis (Qoomes), but was destroyed by the Afghans in 1723. Few remnants of that time remain; one is the ruined Tari-khaneh mosque with a number of massive columns and wood carvings and two minarets of the 11th century. The remains ofHecatompylos lie to the southwest of the city, extending from Forat, 26 kilometres (16 mi) south of Damghan, to nearly 32 kilometres (20 mi) west. On an eminence in the western part of the city are the ruins of a large square citadel with a small white-washed building, called Molud Khaneh (the house of birth), in which Fath Ali Shahwas born (1772). The Tari-khaneh (c. 9th century), possibly the oldest known mosque in Iran, still stands in the city.
To the southeast of the city there is ruin of a castle from the Sassanids now called Tappeh Hessar, which is thought to be a garrison. After excavation in 1996, archeologists announced that the area ruins indicated three layers from three different eras. The oldest one dates back to 4000 BCE when the Aryans settled in the Iranian plateau.
Despite 7,000 years history, Damghan has been forgotten beneath desert sand dunes, It is one of the most ancient urban metropolis in the Iranian plateau, with many historical monuments including Tappeh Hessar which belongs to the Median (728-550 BCE), Parthians (248-224 CE) and Sassanid (224-651 CE) dynastic periods — the Tarikhaneh was built as a fire temple during the Sassanid dynasty and converted into a mosque after the advent of Islam – and many other historical buildings belonging to Seljuks and other periods.