Short answers, pulled from the story.
A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass, or ceramic, held in place by plaster or mortar to cover a surface. Traditional mosaics use small cubes of stone or hand-made glass enamel known as tesserae; modern mosaics may also incorporate shells, beads, coins, bottle caps, and found objects.
The earliest known mosaics made of different materials were found at a temple building in Abra, Mesopotamia, and date to the second half of the third millennium BC. They consist of pieces of colored stones, shells, and ivory. Pebble mosaics also appeared in Mycenaean Greece at Tiryns, and figural mosaics became widespread in classical Greece and Rome.
The Villa Romana del Casale near Piazza Armerina in Sicily holds the largest collection of late Roman mosaics still in their original location and is a UNESCO World Heritage Site. Its most notable images include the 64-meter Great Hunting Scene and the Bikini Girls. The Bardo Museum in Tunis, Tunisia, also holds an extensive collection of mosaic floors from Roman villas across North Africa.
The Norman kings of 12th-century Sicily adopted Byzantine mosaic tradition to reinforce the legitimacy of their rule. Greek masters working in Sicily blended Byzantine, Western European, and Islamic styles. The Monreale Cathedral mosaics, executed between 1176 and 1186 under King William II, cover 0.75 hectares with at least 100 million glass and stone tesserae, making them the largest mosaic decoration in Italy.
Jewish communities under Roman and Byzantine influence adopted classical mosaic techniques for synagogue floors, combining pagan symbols like the zodiac with Jewish religious imagery. In the synagogue at Sepphoris, Helios sits in his sun chariot at the center of the zodiac wheel, with each sign matched to a Jewish month, while surrounding panels depict biblical scenes such as the binding of Isaac.
The Madaba Map is a mosaic floor made between 542 and 570 in the church of Saint George at Madaba, Jordan. It is the oldest surviving cartographic depiction of the Holy Land, showing an area from Lebanon in the north to the Nile Delta in the south, with Jerusalem depicted in the greatest detail at the center. It was rediscovered in 1894.