Gek Terna S.A., together with its subsidiaries, engages in the construction, energy, industry, real estate, and concession businesses in Greece, the Balkans, the Middle East, Eastern Europe, the United States, and internationally. It operates through Constructions; Electricity from RES; Electricity from Thermal Energy and HP Trading; Real Estate; Mining/Industry; and Concessions. The company involves in the construction of public and private projects, including road and railway networks, building, hospitals, museums, industrial facilities, hydroelectric projects, dams, power plants, etc.; financing, construction, maintenance, and operation of concession projects, such as motorways, airports, parking stations, unified automatic collection system, and municipal waste treatment plant. It also produces electricity from wind generators, hydroelectric projects, natural gas, solar, biomass, fuels, and other renewable energy sources, as well as trades in electric energy and natural gas. In addition, the company purchase, develops, manages, and sells real estate; produces quarry products; and exploits magnesite quarries. Gek Terna S.A. was formerly known as Ermis Real Estate Constructions Enterprises S.A. The company was founded in 1959 and is headquartered in Athens, Greece.