in Athens, Greece. Much of the original marble which formed the roof and frieze now forms a pile of rubble at its base.]]This article is about ruins in architecture; for other meanings, see Ruins .Ruins is a term used to describe the remains of man-made architecture: structures that were once complete but which have fallen into a state of partial or complete disrepair, due to lack of maintenance or deliberate acts of destruction. Natural disaster, war and depopulation are the commonest root cau