was a north-south oriented street in Roman cities, military camps, and coloniae. The cardo, an integral component of city planning, was lined with shops and vendors, and served as a hub of economic life.
columns resembling human; seen on the Erechtheon; the caryatids sided with the Persians- therefore must bear the weight of the entablature forever
center: focus point (pyramid, dolman)
perimeter: encloses space (Diocletian's Palace, Great Wall)