Perched on top of a ridge of rock in the Aude Department of Languedoc-Roussillon in southern France, on the edge of the Pyrenees, sits the Cathar castle of Peyrepertuse.
“The castle is one of the “Five Sons of Carcassonne” along with the castles Quéribus, Puilaurens, Termes, and Aguilar, all situated atop ‘unassailable’ rocky peaks.” – Wikipedia
The Cathars were a religious group, persecuted for their beliefs, who retreated to these strongholds but were unable to withstand the siege laid by their persecutors and were, essentially, wiped out.
Atop Jungfrau on the Aletsch Glacier in Switzerland sits the Sphinx astronomical observatory – one of the highest observatories in the word at 11, 716 feet.
Atop Aiguille du Midi in the French Alps there is a cable car station, barely discernible from our hotel window in Les Houches.