In 1875, Eiffel et Cie were given two important contracts, one for a new terminus for the line from Vienna to Budapest and the other for a bridge over the river Douro in Portugal.
6. oktobra 1868 je stopil v partnerstvo z Théophile Seyrigom, ki je kot Eiffel diplomiral na "École Centrale", in ustvaril podjetje "Eiffel et Cie".