An out-of-place artifact (OOPArt) is a term for a historical, archaeological or palaeontological object found in a very unusual or seemingly impossible location. The term covers a wide variety of objects, ranging from material studied by mainstream science, such as the Iron pillar in Delhi, to so-called "forbidden archaeology" that is far outside the mainstream.
While occasional discoveries, such as the Antikythera mechanism, have led to scientists reassessing the technology of ancient civilizations, most believe cases of OOPArt to be the result of mistaken interpretation, wishful thinking, or extreme cultural centrism - the belief that a particular culture couldn't have created or done something because they were too ignorant or simply not smart enough. Supporters regard them as evidence that mainstream science is overlooking huge areas of knowledge, either willfully or through ignorance. (Wikipedia)