The Byzantine Empire ruled from Constantinople for over a thousand years, and historian John Romer traces its rise and fall through the buildings and objects it left behind. He walks the Hagia Sophia in Istanbul, describing the construction techniques behind its dome and mosaics, then moves to the Basilica of San Vitale in Ravenna, where Byzantine mosaics depicting the life of Christ once instructed a congregation that could not read. In Venice, the Treasury of San Marco holds silks, carved ivory, and precious metalwork that made their way west along Byzantine trade routes, evidence of an empire whose wealth outlasted its borders. Romer also covers the political history: Justinian's reign and building program, the court intrigues and invasions that followed, and the Fourth Crusade, when Christian armies sacked Constantinople rather than an outside enemy. The film uses these sites and objects as physical evidence for how the empire actually worked, rather than presenting Byzantium as a footnote between Rome and the Ottoman conquest.