The incredible £100bn two new cities and world's longest bridge connecting Africa to Asia

A hugely ambitious project that could transform the economic fortunes of two countries hangs in the balance. Estimated to cost a cool £100 billion, the project envisages the construction of two futuristic metropolises powered by renewable energy sources.

Linking the two cities will be a 20-mile suspension bridge connecting two continents - Africa and Asia. The inspiration behind the dream is none other than Sheik Tarek Bin Laden, brother of the infamous Osama. The two cities will be built in Djibouti and Yemen respectively and will be "the envy of the world", according to the Sheik.

The African city will be home to 2.5 million people, while its Middle Eastern counterpart will have a population of 4.5 million.

Sustainability is at the heart of the project, with both cities to be built completely with green technologies and powered by renewable energy.

The metropolises will be equipped with the best hospitals and schools, as well as top class universities and sporting facilities.

The hope is the project will turn Djibouti into a major economic hub as it becomes a key link between Africa and Asia.

The African country's access to the sea allowed it to benefit economically in the past, following Eritrea's independence.

This forced Ethiopia to re-route its trade via Djibouti's main shipping port, bringing in much needed revenue.

The proposed Bridge of Horns over the Red Sea will have six-lanes for cars, carrying up to 100,000 vehicles per day.

At the same time, four rail lines will transport up to 50,000 passengers on a daily basis.

As the Bab-el-Mandeb strait's waters are up to 300 metres deep, the bridge's towers would have to be 700 metres high - 400 metres of which would be above water - to support the structure.

However, the ambitious plans have yet to be signed off by the governments of either country and is therefore still in limbo.

Revealed originally in 2008, the project remains at the planning stage with many sceptical that it will ever see the light of day.

Djibouti's government, though, appears keen to go ahead with the project, having set aside hundreds of square miles of land for the creation of its new city.