If completed, the currently nameless city would span 700 sq km (a space almost as big as Singapore), house a park double the size of New York's Central Park, and a theme park four times as big as Disneyland – all to be completed within five to seven years.
"Since the 2004 peak of 27,000 sq km of forest destroyed, matters have improved with regard to deforestation," he says, when I call him.
The pivotal moment for Northumberland came in 2013 when the entire national park housing Hadrian's Wall, along with Kielder Water and Forest Park, some 1,500 sq km, was awarded Dark Sky Park status, the only one in England.
Researchers identified five key traits of a well-managed marine park – no fish take, well enforced, established for longer than 10 years, larger than 100 square km and isolated by deep water or sand.
In the summer, the place to be is Patagonia, the southern territory extending over nearly 750,000 sq km of largely unspoilt landscape.
But the 'Fantasy' has now travelled 300,000 km, and Karakvin says it has a maximum speed of 140 km/h.
In the mid-19th century, Majuli was about 1,200 sq km in area and was a contender for the title of world's biggest river island; now it is barely 400 sq km, about the size of the Isle of Wight, and surveys predict that it will disappear within 20 years.
El Salvador, central America's smallest country, is also its most densely populated: in 2012 there were 304 people per sq km.
Pressed by the Guardian, Madbouly said he already had the money to build at least 100 sq km of the new capital, including a new parliament.
Distance 2.8 miles/4.6 km Typical duration 1 hour Start and finish Sheffield Cathedral Start postcode S1 1HA Step-by-step details and maps ramblers.org.uk/sheffield This is a lovely varied walk from Sheffield city centre, starting at the cathedral and heading along the river Don to Kelham island and past the Kelham Island Museum.
