Turkey opened the world’s first underwater rail link between two continents yesterday, connecting Asia and Europe and allowing Prime Minister Tayyip Erdogan to realise a project dreamt up by Ottoman sultans more than a century ago.

The engineering feat spans 13 kilometres to link Europe with Asia some 60 metres below the Bosphorus Strait. Called the Marmaray, it will carry subway commuters in Europe’s biggest city and eventually serve high-speed and freight trains.

The 5.5 billion lira (£2 billion) tunnel is one of Erdogan’s “mega projects”, an unprecedented building spree designed to change the face of Turkey.

They include a 50-kilometre canal to rival the Suez that would render half of Istanbul an island, an airport that will be the world’s busiest and a giant mosque on top of an Istanbul hill.

Atomic power stations are on the drawing table. A third bridge over the Bosphorus, whose construction has already felled one million trees, is under way.

The plans have fired up Erdogan’s opponents who dub them “pharaonic projects”, symptom of an increasingly authoritarian style of government, and warn of environmental catastrophes in one of world’s most earthquake-prone nations.