The double-headed eagle serves as the Russian coat-of-arms. Where did it originate?
It was taken over from the Byzantine Empire. After the fall of Constantinople in 1453, Moscow claimed succession to the legacy of the Eastern Roman Empire. Ivan III married Sophia Palaiologina, the niece of the last Byzantine emperor Constantine XI, and made the Byzantine double-headed eagle his own, and eventually Russian, coat-of-arms. In Byzantine heraldry, the heads represent the Emperor having authority over both secular and religious matters.