Kahler Asten, Mountain summit in Hochsauerlandkreis, Germany.

Kahler Asten is a 841.9-meter summit with an observation tower and weather station at the peak. From the top, visitors can see across the rolling hills and forests of the Sauerland region.

The summit's weather station was permanently staffed until 2016, when the last manual report was sent on 22 March at 14 UTC; since then it has operated unmanned. The site was first protected in 1965, when the Arnsberg district government designated the high heath around the peak as a nature reserve, renewed in 1983 at 36 hectares and again in 2008 at 48.6 hectares. A 53-hectare FFH area was added by the state in 2006.

The summit carries the nickname "roof of Westphalia", although the 843.2 m Langenberg on the Hessian border is higher; older sources gave the Kahler Asten only 830 m. The Lenne rises in a captured spring on the crest at 825 m, the highest river source in northwest Germany. A plaque set in boulders reads "KAHLER ASTEN", with a small channel of water running below it.

Multiple hiking routes lead to the summit from nearby villages, each offering different difficulty levels and walking times. The mountain is fully accessible on foot with clear pathways throughout the year.

The summit sits on the watershed dividing the Rhine and Weser rivers, with the Lenne river sourcing here. This spring is the highest river source in northwest Germany.