The solea, or sandal, was the most common indoor shoe of the ancient Romans. It was a very simple shoe, consisting of a flat sole held to the foot with a simple strap across the instep, similar to today's thongs or flip-flops. Most of the solea known to historians were made of leather. Some, however, were made of wood. Special wooden-soled sandals, called sandalium, were worn by women during the Roman Republic (509–27 B.C.E. ) and were later worn by both sexes. It appears that simpler wooden-soled solea were also worn by poorer Romans.
A respectable Roman citizen never wore his or her solea outdoors, just as they never wore their outdoor shoes, or calcei, indoors. When wealthier citizens went to someone else's house or to a public event, they had their servants carry their solea and they changed into them when they arrived at their destination. In fact, the Romans had a saying that related to this custom. To "ask for one's sandals" indicated that one was ready to depart.
There were alternatives to the leather solea. The baxea was very similar to the solea. It had a strap that rose up between the first two toes and was anchored in another strap that crossed the instep of the foot. The baxea were typically made of papyrus leaves or other vegetable fibers that were woven into a durable, thick sole. It is thought that these inexpensive sandals were adopted from the Egyptians, who wore a similar sandal as early as 3100 B.C.E.
Symons, David J. Costume of Ancient Rome. New York: Chelsea House, 1987.
Yates, James. "Solea." Smith's Dictionary: Articles on Clothing and Adornment. http://www.ukans.edu/history/index/europe/ancient_rome/E/Roman/Texts/secondary/SMIGRA*/Solea.html (accessed on July 24, 2003).