But the church is interesting not only architecturally, but historically. It has never been used for the worship of Islam. It could be restored in a few hours to the worship of the Christian Church. Its incongruous contents, too, have an interest. There are weapons of the Crusaders, chainmail, great swords; the curious machines of Alexius Comnenus; keys of conquered cities, bags of earth in token of conquest. There are five fine bells, two with dates 1600 and 1658, one dedicated "Vero Deo Patri Filio Spiritui Sancto." There are swords of the Janissaries, and their curiously shaped helmets, and their famous kettle drums, differing in size according to the number of companies that were assembled. Most interesting of all, perhaps, are the fragments of the great chain which stretched across the Golden Horn. In the court are two fine sarcophagi, which are called those of Constantine and Irene. [Illustration: COMPARATIVE SIZES OF GREAT AND LITTLE S. SOPHIA.] [Illustration: PLAN OF SS. SERGIUS AND BACCHUS.] These two examples of the basilican style are clear and distinct. There are other churches which have basilican features, but do not belong to the period before Justinian, and are worthy of detailed examination. S. Thekla stands back from the walls on the Golden Horn not far from the gate now called Aivan Serai Kapoussi, which was once the Porta Kiliomené. The foundation of this is not earlier than the ninth century, and Anna Comnena mentions its restoration in the eleventh. It is a curious survival of an early style, for it has no dome, and is simply a basilica about forty feet long and twenty broad, with an apse. It was gaily restored a few years ago, and bears as a mosque the name of Toklou Ibrahim Dedeh Mesjid. S. Theodore Tyrone (Killisé Djami) stands not far to the west of the mosque of Suleiman. It was built about 450, but much of the present building is of the twelfth century. It is not improbable that in its chief features it may be older than any church in Constantinople. The central dome has ten arches, perhaps originally windows, now closed. All the domes are small, and the columns are without ornament. There are narthex and exo-narthex, and in the latter is a mysterious opening, full of stones and fragments of mortar, leading, it is said, to a long passage which the Turks fancy once led to S. Sophia.