Créac’h lighthouse on the island of Ouessant in Brittany is one of the most powerful in the world – the light is visible for 60km. The 55m stone tower was built in 1863 and was electrified in 1889. The old engine room and other buildings around the base of the tower are a large museum that tells the story of signalling at sea from ancient times to the present. The authoritative national collection includes the artefacts of the Trocadéro lighthouse service depot in Paris. The displays explain the technological evolution of maritime signalling and its importance for the safety of shipping. On show are lanterns, beacons, optics, buoys, models, documents and artefacts from shipwrecks. A star item is the pioneering dioptric device designed in 1823 by Augustin Fresnel, which influenced the whole future of lighthouse operation. Audio-visuals give an impression of the lives of lighthouse keepers. Nearby is a preserved semaphore tower.