A colonnade is a series of columns spaced at regular intervals.
For example, all four sides of a classical Greek temple have
colonnades, which support the roof of the building.
Colonnades are also used in an arrangement called a portico.
Finally, colonnades can be freestanding, supporting a simple
series of stone or wooden beams, as in the case of a pergola.
Two of the most impressive series of colonnades in the United States
are on the front and back façades of the U.S. Capitol.