stoa

thumb|300px|The restored Stoa of Attalos in Athens, with busts of historical philosophers.

A stoa (; plural, stoas, stoai, or stoae ), in ancient Greek architecture, is a covered walkway or portico, commonly for public use. Early stoas were open at the entrance with columns, usually of the Doric order, lining the side of a building; they created a safe, enveloping, protective atmosphere.