The church of the Ayioi Apostoloi was once the katholikon of a monastery dedicated to the Panayia Gorgoepekoos (Virgin Swift to Succour) founded by the patriarch Niphon in 1310-14.
It is a composite cross-in-square structure with dome, arcades on three sides, double narthex, and superb tile decoration on its exterior surfaces. The great diversity in the architectural arrangement of the exterior of the church has produced in the interior a variety of surfaces that have been decorated with mosaics and wall-paintings.
The mosaics, executed before the dismissal of Niphon, are masterpieces of Palaeologan art. Their noble and elegant figures avoid any exaggeration of dramatic expression. The wall-paintings executed in about 1330, following the restoration of Niphon by Andronikos III, are not so different from the painting done in the decade 1310-20, but they have acquired a more articulate character.