I find locations known from various historical sources but unknown in the real physical world fascinating. In classical studies these were for long a norm and the antiquarians spent lifetimes pondering over the location of such mythical places as Crustumerium or Fidenae. These places were found and confirmed only through archaeological fieldwork, which was something the early antiquarians normally were not accustomed to do. Only after Schliemann found Troy exploring became a norm although historians often restricted themselves to observing potential locations without looking for material evidence.
A very recent example nearer the home where only through archaeological exploration a mythical place has become reality is the battlefield of Bosworth in southern Leicestershire. Immortalized by Shakespeare in his play Richard III this location was even celebrated with a visitors’ centre, currently the only one adorning a battlefield in England, even if its precise whereabouts were not clear. Only recent survey and coring work, presented also in Time Team, has established the true location of the battle of Bosworth. Before 2010 the battlefield was a matter of theorizing, a theoretical landscape.
This idea of mental landscapes that moved around and did not even exist in the end is captivating. Because of the changes in physical landscape at Bosworth it was impossible to locate the swamp that was the defining feature of the battlefield and its surroundings without entering private land and coring for the marshy layers below the surface. This did not hinder historians such as Peter Foss from trying to decipher the place from later descriptions of the battle and explain the different movements during the battle in their chosen location. These interpretations turned out to be fictional and imaginary but they create a sort of alternative reality now when revisited after the surface finds of cannonballs and armour fragments as well as the rediscovery of the swamp have revealed the true battlefield and allow reconstructing the strategic moves in their real locations.