The Byzantine Empire has existed longer than all the empires that were on Earth — more than 1000 years. She created the «Byzantine Commonwealth» of countries (D. D. Obolensky’s term), stretching from the South Baltic to the Mediterranean and from the Adriatic Sea to the Caucasus Mountains. The Commonwealth countries had religious and cultural unity, a close political culture and a similar tragic fate. All of them fell victim to foreign conquest, from the Mongols to the Ottomans, and with great difficulty, centuries later, regained their sovereignty. With the death of the Byzantine Empire in 1453, its historical role did not stop. Byzantium remained a relevant historical actor for a long time, as an ideal and as a symbol, as a heritage and a...