57.2667°N, 16.7833°E.
Bla Jungfrun Trolleborg is a prehistoric or medieval stone-formation labyrinth in Kalmar County, Baltic Sea, Sweden. The design is a classical 11circuit layout with 11 circuits, 12 walls, approximately 22 metres in diameter, built of stone. Documented age: Unknown (island sacred since ~8500 BC, labyrinth date unknown). Current condition: intact. The largest stone labyrinth in Sweden occupies Bla Jungfrun ('Blue Maiden'), a sacred island in Kalmar Strait where ritual activity dates back 11,000 years. Quartz shards from approximately 8500 BCE prove the island's significance predates agriculture. Documentation sources: Kraft 1983, Kalmar Museum. A figure that resolves into a single unbroken line when traced from edge to centre and back.
The labyrinth is one of several hundred sites of this type catalogued globally; each preserves the same unicursal walking-pattern with regional variation in scale, material, and date.