Missile-related research and development occurred at the Lavizan Technical and Engineering complex in Tehran. According to Melman and Javedanfar, "several of Iran's most secret and prestigious projects have been developed there," including the country's first generation of liquid-fueled missiles. [1] In 2003, Lavizan reportedly opened a solid fuel production facility. [2] However, satellite images obtained by ISIS showed that Iran scrapped the entire complex in 2004 after the IAEA had asked for permission to carry out an inspection. [3]

Sources:
[1] Yossi Melman and Meir Javedanfar, The Nuclear Sphinx of Tehran (New York: Basic Books, 2008), p. 132.
[2] Bharath Gopalaswamy, "Iran's Missile Program," BASIC Getting to Zero Papers, No.4, British American Security Information Council, 15 July 2008, www.basicint.org.
[3] "Nuclear Sites, Lavisan-Shian," ISIS Nuclear Iran, Institute for Science and International Security, www.isisnucleariran.org.