There are some twenty-five other buildings in Stamboul that were originally Byzantine churches. That is, of course, but a small proportion of the multitude that astonished Villehardouin and his men. Covering as they do a period of ten centuries, however, they exhibit most interestingly the gradual development of ecclesiastical architecture from the Roman basilica to the high-domed trefoil church of the fourteenth century. This development is not always easy to follow, as in some cases the churches have been much altered to suit Turkish needs. The orientation of a mosque, for instance, differs from that of a church, since the _mihrab_ must face Mecca, and actual changes of structure have occasionally resulted. Then, of course, all interior decoration too visibly representing Christian symbols or the human form has been destroyed or covered up. And a good deal of exterior brickwork has disappeared under plaster and whitewash. Consequently the prowler in Stamboul is on the look-out, if he have the least tinge of archæology in him, for anything that may hint at a pre-Turkish origin. Not that very much can remain above ground to discover. After so much careful searching it will only be a small built-in structure or fragment that will come to light. But several of the attributions of churches are disputed. Their true names were lost with their original worshippers, and it is a comparatively short time since Christians have been free to circulate at will in the Turkish quarters of Stamboul. And there is reason to hope that under many a piece of baroque stencilling an old mosaic waits to be laid bare.