During the 1970s and 1980s, ENKA in cooperation with international partners undertook various construction projects in Türkiye, as well as abroad in Saudi Arabia, Libya, Jordan and Iraq. As a result of strategic, cooperative business ventures with foreign firms, ENKA, together with a German partner, was awarded an international tender for the first time in 1970, to construct the Ortaköy Viaducts and approach roads to the 15 July Martyrs Bridge (Bosphorus Bridge).