A column is a cylindrical vertical support that usually tapers towards the top in the manner of a tree trunk. Columns can be freestanding or engaged, which means they are attached to a wall. Engaged columns do not provide structural support. Conventional columns that follow the traditional Greek Classical Orders feature a base, shaft, and capital (also see “Art of the Ancient World, c. 5000 B.C.E. to 400 C.E.”) A pier is generally much larger than a column and is usually made of stone, brick, or concrete. Piers act as vertical supports for masonry constructions such as arcades.