The Channel Tunnel, connecting Britain with France through a 50km underwater passageway, has been transporting passengers for 20 years.
Running from French port town Calais to Folkestone in Kent, the UK, the Channel Tunnel saw its first passengers – the British monarch Queen Elizabeth II and former French President Francois Mitterrand on 6 May 1994.
The Queen was the first to take a ride through the tunnel on a Eurostar train, as she travelled from Folkestone for the first opening ceremony held in Calais, where she met with Mitterrand who came on another Eurostar train from Paris.
After the ceremony, which started with both trains stopping nose to nose, the two heads of state boarded a Le Shuttle train, transporting vehicles through the tunnel, to travel to Folkestone for the second celebration.
However, after the official opening, it took several months before the £4.650bn tunnel, named one of the modern engineering wonders by the American Society of Civil Engineers in 1994, started ferrying regular passengers.
With its deepest sections 75 metres below the seabed and with nearly 38 kilometres running under the English Channel, the tunnel has the longest undersea section in the world.
Although the idea to improve transport links between France and the UK by digging a tunnel under the sea was first discussed as early as 1802, political pressure and safety concerns stalled the initiative until the 1980s.
On the British side, fears of illegal migrants using the tunnel to reach Britain as well as animals carrying rabies passing through were among the biggest concerns.
Eventually, Eurotunnel pushed the projects through, launching construction on 1988. Construction began on both sides with eleven tunnel boring machines cutting through chalk marl to construct two rail tunnels and a service tunnel.
The project was finished one year after the original schedule and piled up an 80 per cent cost overrun. At the peak of construction 15,000 people were employed with daily expenditure over £3m.
Ten workers, eight of them British, were killed during construction between 1987 and 1993, most in the first few months of boring.