Between a rocky hill near Horn-Bad Meinberg in Externsteine, Germany, and a stone circle in Bad Meinberg, the Teutoburg Forest had a network of ley lines known to local wizards as the Holy Lines (heilige Linien)—ley lines were ancient, straight tracks in the landscape, invisible lines believed to mark the locations of the land's spirituality and mystery, capable of generating or gathering magic and soul power. In areas with such high concentrations of magic, there were often magical ruins left behind by ancient wizards, much like Stonehenge in the United Kingdom. These places themselves also emitted "energy" and "abilities" that wizards could develop and use. In many countries, Unspeakables of the Department of Mysteries, as well as members of similar institutions, made use of such places to investigate and experiment with mysterious powers.
Beneath the forest cover of the Teutoburg Forest, inside the ruins of a vast ancient temple, several Crystal Balls permanently enchanted with Lumos floated in midair, giving off a hazy glow in the dim underground hall.
The place was extremely spacious. Broken stones lay scattered across the hall, and Death Eaters were stationed at the entrance to cast spells at regular intervals; otherwise, the air inside would soon become unbearably foul. Fortunately, the special geography here made spellcasting easier. Though it could not compare to the Floating City under the radiation of the Energy Core, it still made these preparations feel far easier for the Death Eaters.
To the north of the hall, besides the rows of remaining corridor columns, there were black mounds of earth that had been dug up from underground and piled together. At the excavation site, many stone pillars were scattered across the northeastern earthen wall, their surfaces still streaked with mud stains.
Some gorgeous reliefs remained on the walls of this room,