Stoa (/ˈstoʊə/; plural, stoas, stoai, or stoae /ˈstoʊ.iː/) in ancient Greek architecture; covered walkways or porticos, commonly for public usage. Early stoas were open at the entrance with columns, usually of the Doric order, lining the side of the building; they created a safe, enveloping, protective atmosphere.
Later examples were built as two stories, with a roof supporting the inner colonnades where shops or sometimes offices were located. They followed Ionic architecture. These buildings were open to the public; merchants could sell their goods, artists could display their artwork, and religious gatherings could take place. Stoas usually surrounded the marketplaces of large cities.
The name of the Stoic school of philosophy derives from "stoa".
Read more about Stoa: Famous Stoae