The art of mosaic has been represented in works both religious and secular down through the ages. Greek, Roman and Byzantine craftsmen created stunning presentations through the use of glass, stone and even shells. But nowhere in the world has the execution of mosaic taken such a dramatic turn than in the art of the Vatican mosaicists. It is in Rome that the finest collection in the world of tesserae, the tiniest of stones from which their work takes form, is found. more on this