Greatest light range for a lighthouse

According to the USA's National Geospatial-Intelligence Agency, which maintains a global archive of navigational beacons (i.e., the "List of Lights, Radio Aids and Fog Signals"), the lighthouses installed with the brightest lights active as of Sep 2022 are two sites in Brazil: both the Abrolhos Lighthouse on Ilha de Santa Bárbara, the largest island in the Abrolhos archipelago off Bahia, and the Ilha Rasa Lighthouse, south of Rio de Janeiro, have flashing white lights rated with a nominal range of 51 nautical miles (94.5 km; 58.7 mi). Both lighthouses are maintained by the Brazilian Navy.

Abrolhos Lighthouse is 22 m (72 ft) tall, made of cast iron and was completed in 1861. Ilha Rasa Lighthouse is 26 m (85 ft) tall, made of stone and was completed in 1829; originally using oil lamps, since 1951 its light has been electric, powered by diesel engines. A key reason for the extreme light range of these lighthouses is that they are fitted with mesoradial lenses (installed in 1898 and 1909, respectively), an extremely large Fresnel lens with a focal length of 1,125 mm.

It's worth noting that "nominal range" relates to the maximum possible range for a light on a clear day and does not take into account prevailing weather conditions which might impact visibility (the "luminous range") or the curvature of the Earth/position of the observer (the "geographic range").

The brightest lighthouses in Europe and Africa, respectively, are Créac'h Lighthouse in Ouessant, Finistère, France, and the "new" Cape Point Lighthouse in South Africa, both of which are said to be visible 60 km (32.5 nautical miles; 37.3 miles) out at sea.

Historically, there were navigational lights with an even greater range, though not necessarily in a "traditional" lighthouse structure targeted at maritime travellers. For instance, four-arc mercury bulbs placed on the top of the Empire State Building each had a rated candle-power of 450 million and were visible 130 km (80 mi) away at ground/sea level and 490 km (300 mi) away from aircraft. They were activated for the first time on 31 March 1956 but are no longer in place.