Recent research is making us daily better acquainted with Byzantine religious buildings. Saint Sophia is a byword in architectural history and the Byzantine style has been drawn on in the West perhaps more than any other. But of the secular buildings of Byzantium, of the great palaces so famous in history, few examples have been spared. Accounts tell us of the great palace at Constantinople, but of this vast collection of buildings little more than a single stair remains above ground. Of the palace of the Hebdomon, situated on the Sea of Marmora to the south of the capital, even less is to be seen, though further excavations would probably prove fruitful, and of the mediaeval palace of the Blachernae on the Golden Horn, which served as the Imperial residence after the eleventh or twelfth century, only a single building, the Tekfour Serai, survives.