Tuesday marks the 126th anniversary of the day the Eiffel Tower opened to the public in Paris.
The event is being marked by a Google Doodle, with an illustration of six workmen jauntily putting the final touches to the iconic building.
On March 31, 1889, French engineer Gustave Eiffel unfurled the French tricolor from atop the tower, officially marking its completion.
The 324-meter (1,063ft) iron-lattice tower is the world’s most visited paying attraction and was erected for the 1889 World Fair.
Last year a series of four glass viewing sections were installed at its first level, costing €30 million.
On Saturday the tower went dark briefly to mark Earth Hour, the campaign to raise awareness about climate change.
The five-minute dark-out on Saturday night was a symbolic gesture in the City of Light.
Cities around the world also marked the event, with other landmarks like the Kremlin and the Empire State Building going dark.
France has been preparing for months to host an international climate conference in Paris at the end of the year, pressing nations to set attainable goals for reducing greenhouse gases and mobilizing international finances to fight climate change.
Earth Hour was launched in 2007 by the World Wildlife Fund to encourage awareness of environmental issues. The idea is to turn off lights for an hour — not possible for safety reasons for the Eiffel Tower.