Altars of any faith or culture that are not connected to or supported by a building or other structure. The term typically includes outdoor altars, and altars that are placed within a building but are not architecturally attached to the walls or structure of the building. Note that in some cases, particularly in certain periods of Catholic architecture, it may at first glance appear that an altar is attached to the wall, but it is in fact freestanding in keeping with the ecclesiastical prescription that the high altar must stand free on all sides, although the backs of smaller altars may be built against the wall.