The complex houses irreplaceable works of art: mosaics, the best collection of early icons in the world, many in encaustic, as well as liturgical objects, chalices and reliquaries, and church buildings. The large icon collection begins with a few dating to the 5th (possibly) and 6th centuries, which are unique survivals; the monastery having been untouched by Byzantine iconoclasm, and never sacked. The oldest icon on an Old Testament theme is also preserved there.