THANK THE ancient Romans for mosaic tiles -- a home decorating idea that seems straight from the pages of Martha Stewart.

Visual Arts professor Guy Métraux, who studies them, says the Romans produced some of the largest and most elaborate mosaics in history.

"Filling an entire house wasn't unusual," says Métraux. "That could easily mean 90,000 pieces. An average-sized living room might be done in a month, but larger projects could take half a year."

Roman mosaics are a technical wonder, he says. Thousands of one-centimetre-square tiles of coloured marble or limestone were inset into plaster or brick floors. Mosaic clients usually were the rich, government and early churches.

Coloured borders like braid work or diamonds were common designs, says Métraux. Inside would be the focal point - perhaps a religious figure, picture of a battle, a flower, or an animal such as a bull.