The highest point of the Harz, where German tradition has witches gathering on Walpurgis Night — Goethe sent Faust there. The mountain gave its name to an optical effect: the Brocken spectre, the observer's own vast shadow cast on cloud below with a rainbow halo round the head. The effect is real and explicable, and probably lies behind a share of the stories of encounters at the summit.

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Uluru

A massive sandstone monolith in central Australia that shifts from ochre to deep red at sunset. For the Aṉangu people it is a sacred site with its own rules about what may be photographed and where one may not climb.