The Stob Earth Pyramids (Bulgarian: Стобски пирамиди) are rock formations, known as hoodoos, situated at the foothills of the Rila mountain range in south-western Bulgaria. They span an area of 0.7 km2 near the village of Stob, Kyustendil Province. The rock formations are up to 12 m high and up to 40 m thick at the base. Their shape is mostly conical to mushroomlike. Some of the columns are topped by flat stones.

+Info : https://en.wikipedia.org/wiki/Stob_Earth_Pyramids