According to Karl Benjamin Preusker, several rocks in Upper Lusatia were considered prehistoric offering altars. Among these he counted a rock on Bieleboh, the so-called Bieleboh altar. Local historians from Sohland an der Spree examined this presumed altar for its possible calendarial use for observations of the sun in 2007. It could be shown that an eye-shaped opening through the rock, the Teufelsauge (devil's eye), allows to determine the day of the equinox when the light of the rising sun passes through it.