The Roman Empire in the East, founded by Constantine - the Great in 330 AD, was virtually unique in bridging the transition from GraecoRoman antiquity into the medieval world and on into the dawn of the Renaissance. Byzantium was a strange, hybrid culture, partly Eastern, partly Western, and partly an amalgam of many elements: for centuries it was Europe's bastion against Islam, until the terrible Sultan Mehmed, aged only 21, finally sacked Constantinople in 1453 and made it the Ottoman capital. By then the so called empire was impoverished and shrunken, having suffered as badly from the Crusaders as it did from the Turks or Egyptians, and was also hated by the Papacy for its refusal to give up its Greek Orthodox beliefs (the Byzantines were equally intolerant on their side). John Julius Norwich begins with the reign of Alexius in the 11th century, which heralded a recovery of sorts after the disastrous defeat at Manzikert a few years before; but most of his chronicle, alas, is a dying fall.