Manzariyah is a facility for research and development on unguided missiles and missile fuel production.[1] Its exact location varies in open source literature. Manzariyeh refers to several locations in Iran, including a Revolutionary Guards Training Center northeast of Tehran located in the same region where several sources put the missile facility. However, a study by the Center for Strategic and International Studies puts the site's location southwest of Tehran, close to Arak. [2]. Although the facility is presumably operational, more detailed information is not available.

Sources:
[1] "Manzariyeh," Federation of American Scientists, www.fas.org.
[2] Abdullah Toukan and Anthony H. Cordesman, "Study on a Possible Israeli Strike on Iran's Nuclear Development Facilities," Center for Strategic and International Studies, 14 March 2009, www.csis.org.