A colonnade is a series of columns set at regular intervals, flanking a walkway and usually supporting a roof or series of arches. (For a wedding, the columns are often wrapped with garlands of flowers.)
In Edith Wharton's Ethan Frome, a type of colonnade decorates the local post office:
If you know the post-office you must have seen Ethan Frome drive up to it, drop the reins on his hollow-backed bay and drag himself across the brick pavement to the white colonnade: and you must have asked who he was.
