T wo empires compete to bewitch you in this exhibition that offers a double bubble of beauty. It collides the Byzantine empire, whose capital Constantinople was officially inaugurated on 11 May AD330, with the Ottoman Turks who conquered this great city in 1453 and turned it into Istanbul. The combined glories of two lost worlds – the Ottoman empire was dissolved in 1922 – beget an utterly enrapturing blockbuster. I lost all track of time in this dream city of gold and ivory.

Dream city … Ivory relief panel, possibly fifth century. Photograph: Hohe Domkirche Trier, Foto: Ann Münchow

Even the human form is magically transfigured here into mineral and metal. The martyred abbess St Eudokia becomes a Byzantine icon of marble inlaid with coloured glass, wearing a crown of precious stones and an exquisite dress patterned with diamonds and decorated with pearls and emeralds.…