To mark the 25th anniversary of the opening of the Channel Tunnel, here are 25 facts about the modern engineering marvel.
1. The Channel Tunnel is 31.4 miles long, making it the 13th longest tunnel in use (the longest is the Delaware Aqueduct, at 85.1 miles), and the fourth longest used by rail passengers. It has the longest undersea portion of any tunnel in the world (23.5 miles).
2. The project cost £4.65 billion (equivalent to £12 billion today), 80 per cent more than expected. Construction took six years (1988-1994).
3. It was recognised as one of the “Seven Wonders of the Modern World” by the American Society of Civil Engineers, alongside the Empire State Building, the Itaipu Dam in South America, the CN Tower in Toronto, the Panama Canal, the North Sea protection works in the Netherlands, and the Golden Gate Bridge in San Francisco.
4. The first proposal for a tunnel under the Channel was put forward by Albert Mathieu, a French engineer – it included an artificial island half-way across for changing horses. Further proposals were considered by Napoleon III in 1856 and William Gladstone in 1865, while David Lloyd George brought up the idea at the Paris Peace Conference of 1919.