The Derg, officially the Provisional Military Administrative Council, was the military junta that ruled Ethiopia and present-day Eritrea from 1974 to 1987, when the military leadership formally "civilianized" the administration but stayed in power until 1991.
The Derg was established in June 1974 as the Coordinating Committee of the Armed Forces, Police and Territorial Army, by officers of the Ethiopian Army and Police led initially by chairman Mengistu Haile Mariam. On 12 September 1974, the Derg overthrew the government of the Ethiopian Empire and Emperor Haile Selassie during nationwide mass protests, and three days later formally renamed itself the Provisional Military Administrative Council.
Wikipedia https://en.wikipedia.org/wiki/Derg
Address (Unnamed Road), Addis Ababa, Ethiopia
Coordinates 9°1'12.605" N 38°45'4.764" E