Beyond the Baths, on the same side of the road, is the most interesting little church of the two saints Nereus and Achilles, Christian slaves who suffered martyrdom in the reign of Diocletian.  It is supposed that the Nereus whose body reposes in this ancient church is the person referred to by St. Paul in his greetings to the Roman saints at the close of his Epistle—­“Salute Nereus, and his sister, and Olympas, and all the saints which are with them.”  Bolland, in his Acts of the Saints, mentions that he was a servant in the household of Flavia Domitilla, niece of the celebrated Christian lady of the same name, whose mother was the sister of the Emperor Domitian, and whose two sons were intended to succeed to the imperial throne.  This younger Domitilla, although so nearly related to the imperial family, was banished to the island of Pontia, because of her refusal to sacrifice to idols.  Her two Christian servants, Nereus and Achilles, accompanied her in her exile, and were afterwards burned alive, along with their mistress, at Terracina, and their ashes deposited in the same resting-place.  It is a remarkable circumstance that this church and the catacomb where they were buried at first, should have borne the names of the lowly slaves instead of the name of their illustrious mistress, who was as distinguished by her Christian faith as by her rank.  Time brought to these noble martyrs a worthy revenge for their ignoble fate; for when their ashes were taken from the catacomb to this church in the year 524, they were first carried in triumph to the Capitol, and made to pass under the imperial arches, on which was affixed the inscriptions “The Senate and the Roman people to Santa Flavia Domitilla, for having brought more honour to Rome by her death than her illustrious relations by their works.”  “To Santa Flavia Domitilla, and to the saints Nereus and Achilles, the excellent citizens who gained peace for the Christian republic at the price of their blood.”  Jeremy Taylor, in his splendid sermon on the “Marriage-ring,” has a touching reference to the legendary history of Nereus.  The church dedicated to the honour of these Christian slaves has many interesting associations.  It stands upon the site of a primitive Christian oratory, called Fasciola, because St. Peter was said to have dropped there one of the bandages of his wounds on the way to execution.  And its last reconstruction, retaining all the features of the old architecture with the utmost care, was the pious work of its titular cardinal, Caesar Baronius, the celebrated librarian of the Vatican, whose Ecclesiastical Annals may be called the earliest systematic work on Church History.  The church has an enclosed choir, with two ambones or reading-desks in it, surrounding the altar, as was the custom in the older Christian churches.  The mosaics on the tribune representing the “Transfiguration” and “Annunciation” are more than a thousand years old, and are interesting besides as the first embodiments in art of these sacred subjects.  Behind the high altar is the pontifical chair, supported by lions, with a Gothic gable, on which Gregory the Great was seated when he delivered his twenty-eighth Homily, a few sentences of which are engraved on the marble.