A portico or covered colonnade could be called an arch.
In ancient Greece, this type of covered colonnade was called a stoa. They were usually open-air structures used by the general public.
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It's known as a stoa. Seeing that a picture is worth a thousand words, click on the Related Link to see an image of a stoa.
The only word the begins with x and ends with t is xyst, a long portico (covered outdoor hallway) used for training during stormy weather in ancient Greece.
Xystus, a long portico inside a gymnasium. (Ancient Greece)
In classical architecture, a colonnade ( a series or rows of columns, usually supported by lintel) all around the cella (chamber in a temple), and its porch(es). A peripteral colonnade consists of a single row of column on all sides; a dipteral colonnade has a double row all around.
statues were important in ancient Greece because Greece is substantially covered with statues. They separate the polis or city-states.
A large part of Greece is covered by mountains. Mount Olympus in Greece is famous as the 'home' of the ancient Greeks' gods and as the place that gave the Olympic Games its name.
Ancient Greece covered slightly different areas at various times through history, although broadly it covered the same area as modern-day Greece does today. You can see maps in the Sources and related links section, below.
The Stoa was a covered walkway or colonnade in ancient Greece where philosophers like Zeno of Citium and Cleanthes, who founded the Stoic school of philosophy, would teach and engage in discussions with their followers. The Stoa became a central meeting place for Stoic philosophers to impart their teachings on topics like ethics, logic, and natural philosophy.