Kéréon lighthouse, Stone lighthouse monument in Île-Molène, France

Kéréon lighthouse is a grey stone tower on the Men Tensel reef in the Fromveur Passage, southeast of Ushant. Its tapering shaft rises from a wider, darker base at the waterline to a narrow lantern with a gallery and flat roof. Inside, six stacked rooms of rounded plan sit above a basement, and the lantern base extends into a foghorn shelter.

Construction started in 1907, funded by Amicie Lebaudy who donated money in memory of naval officer Charles-Marie Le Dall de Kéréon. The tower was electrified in 1972 and fully automated in 2004, with control transferred to the Créac'h lighthouse.

The interior earned Kéréon the title of last phare-monument: Amicie Lebaudy's 585,000-franc donation paid for mosaic in the stairwell, Hungarian oak panelling and an oak parquet with a compass rose inlaid in mahogany and ebony. The reef's Breton name, Men Tensel, means "grumpy stone". Since automation in 2004 the marquetry is no longer kept up by keepers, though the tower is heated and dehumidified between fair-weather maintenance visits.

The lighthouse sits on a reef in waters with strong currents and is not directly accessible to visitors from the shore. You can view the structure from the water or learn about it from nearby islands like Molène.

On 16 December 1989, a wave burst the two kitchen portholes at 18:10, throwing the keepers and all the furniture down the stairwell and into the sea; seven panes protecting the optic, 42 metres above the water, shattered, yet the light never went out. The keepers covered the optic with tarpaulins.