When in Western Europe the remnants of the Roman Empire were merely small weak states, Constantinople remained the capital of a powerful organized state. It was a state with administrative structures, with legislation that modernized and adapted to its needs, with currency that circulated throughout the world, from the Mediterranean to the Far East, with an educational system that preserved the cultivation of the Greek language and education.

It was an empire based on a hierarchical society, which bequeathed to later generations, besides its own perception of Christianity, some of the masterpieces of world art. This empire owes the present Europe its existence: If the Byzantine Empire had not held back the Arabs, the Seljuks, and the Ottomans for so many centuries, the West would not have had the opportunity to recover.

These are some of the answers that Judith Herrin provides to the question "What is Byzantium?". The Byzantinist and author of the widely read "Women in Purple" ("Okeanida" 2002) guides her readers through all the aspects of this dazzling yet surprising empire that dominated the stage of History for over a thousand years.