There is an old church in Ravenna, Italy, called the Basilica of Sant’ Apollinare Nuovo. It was built in the late fifth or early sixth century, and was originally dedicated to Christ ((Wikipedia, http://en.wikipedia.org/wiki/Basilica_of_Sant’Apollinare_Nuovo)). One of the most singular and unique things about this church is the appearance of gammadia on many of the vestments of the religious figures in the mosaics. John Welch and Claire Foley have described the gammadia thus:
Scholars refer to these markings as gammadia some of them being shaped like the greek letter gamma (Γ). Though similar patterns have been found in several locations the significance of these markings remains unknown to archaeologists and art historians. ((John W. Welch and Claire Foley, Gammadia on Early Jewish and Christian Garments, BYU Studies 36/3, 1996–97. http://byustudies.byu.edu/shop/pdfSRC/36.3WelchFoley.pdf))
Although the ultimate significance of these markings is lost, but there are some scholars who have speculated that they originally had religious meaning:
Goodenough notes that these markings often appear on significant religious paintings and figures. Admitting that his opinion has not been fully substantiated, he nevertheless believes the importance of the . . . art and textiles in which these markings are depicted substantiates the marks’ religious and symbolic significance, calling clothing that contains gammadia “ceremonial garments” with “symbolic force,” perhaps from a “ritualistic treasure” of items, the nature of which “neither the paintings nor the textiles, unfortunately, make explicit.” ((ibid.))
The most spectacular thing about the nave of this church is the mosaic figures which line the walls, all moving towards the figure of the throne of Christ:
The next row of mosaics are a scheme of haloed saints, prophets and evangelists, sixteen on each side. The figures are executed in a Hellenistic-Roman tradition and show a certain individuality of expression as compared to the other figures in the basilica. Each individual depicted holds a code, book or scroll and, like many of the other figures throughout the basilica, each of their robes has a mark or symbol in it . . . To the right is a similar procession of 26 Martyrs, led by Saint Martin and including Saint Apollinare, moving from the Palace of Theodoric towards a group representing Christ enthroned amid four angels. ((Wikipedia, http://en.wikipedia.org/wiki/Basilica_of_Sant’Apollinare_Nuovo)).