A stone circle is an ancient monument. Such a monument is not always precisely circular and often forms an ellipse, or a setting of four stones laid on an arc of a circle. The number of stones can vary between four and 60 purposely erected standing stones, and often contain burial pits or chambers.
Prehistoric stone circles are found in many parts of the world.
A stone circle is different from a henge or isolated monolith, although each of these features is often encountered in a single location. Earlier features, such as the Goseck circle in Saxony-Anhalt, may have served similar religious/calendrical/astronomical purposes, though probably at a much earlier epoch. Stone circles usually date from the late Neolithic / early Stone Age, that is, c. 7000-3500 B.C.
Archaeological evidence, coupled with information from astronomy, geology and mathematics, suggests that the purpose of stone circles was connected with prehistoric peoples’ beliefs, and their construction can be used to infer about ancient engineering, social organisation, and religion. Their precise function will always be open to debate, but a practical purpose could exist in the form of use as a burial ground, a astronomical marker points for use in determining calendar-related event timings, and usable methodologies have been suggested. Since astronomical event timings are intrinsically dependent on location, it is also conceivable that observations taken could form the basis of some understanding concerning geography, and proceeding from that, derivation of standardised units of measurement for not only time, as in the calendar hypothesis, but also for distance.
Because of the timescale involved, many astronomical parameters have changed, further-complicating analysis of the hypothetical purposes of these monuments. Even with modern technology such as computerised star-map simulations, without a firm date in mind, large margins of doubt are unavoidable. Certainly until recently, accurate retrospective calculations of many heavenly events, tied to each given location, made a comprehensive survey of monuments unapproachable. Current technology improves our chance of gaining an insight into possible motives and uses, and perhaps patterns may emerge when large numbers of arrangements are compared systematically by automated means which are able to examine large numbers of sites as well as large ranges of dating.