Engaged columns, so prevalent in classical architecture, do more than simply add visual rhythm to long masonry walls. Called pilasters, these masonry elements serve structural as well as ornamental functions. They remain an effective way to increase masonry's structural capacity. Strong in compression but relatively weak in tension, plain (unreinforced) masonry supports vertical loads easily but has considerably less capacity to resist lateral loads from wind or seismic activity. Lateral support can be provided by horizontal elements, such as floor and roof diaphragms, or by vertical elements such as shear walls within the building. Steel reinforcement and grout in a wall also add strength and stiffness. Incorporarting pilasters, i.e. thicker, stronger wall sections, at intervals along the wall is an alternative way to provide lateral support, in cases where other methods are impractical or uneconomical. For warehouses or industrial buildings that require high ceilings and unobstructed interior spaces, for example, pilasters can provide needed stiffness at lower cost than uniformly distributed reinforcement, and without the expense and wasted space of thicker masonry. In many such cases, they also are used to support vertical loads imposed by roof trusses or beams. Pilasters also are commonly used in free-standing masonry garden or noise barrier walls that have no horizontal support at the top.