Stoa

[3] 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.

This, an "open-fronted shelter with a lean-to roof", is the meaning in modern usage, but in fact the ancient Greeks "made no clear distinction in their speech" between these and large enclosed rooms with similar functions.

[4] Later examples were built as two storeys, and incorporated inner colonnades usually in the Ionic style, where shops or sometimes offices were located.

These buildings were open to the public; merchants could sell their goods, artists could display their artwork, and religious gatherings could take place.

[5] Other examples were designed to create safe, protective atmospheres which combined useful inside and outside space.