Trojaborg on Bla Jungfrun (Island of the Virgin) in the Kalmar Sound off the East coast of Oland. Part of the prehistoric legacy of Northern Europe and Russia are hundreds of unicursal labyrinths (in Sweden called "Trojaborg") laid out with stones. In historical time they supported many customs and traditions - such as a beautiful nubile girl waiting in the center of the labyrinth to be won by her suitor successfully dealing with the obstacle course. But originally they hardly were just for folkloric fun; they must have had a cultic meaning and ritual use. The one on the uninhabited Island of the Virgin, now a National Park, is the biggest and most beautiful among the 300 Trojaborgs that have survived in Sweden. It was first described by Carl von Linnz in the 18th c.