There's Thinking Big - Then There's Atlantropa

From Wikipedia:

Atlantropa was a gigantic engineering and colonization project devised by the German architect Herman Sörgel in the 1920s and propagated by him until his death in 1952. Its central feature was a hydroelectric dam to be built across the Strait of Gibraltar, and the lowering of the surface of the Mediterranean Sea by as much as 200 metres.

The ultimate, Utopian goal of the project was to solve all the major problems of European civilization by the creation of a new continent, "Atlantropa", consisting of Europe and Africa and to be inhabited by Europeans. Sörgel was convinced that to remain competitive with the Americas and an emerging, Oriental "Pan-Asia", Europe must become self-sufficient, and this meant possessing territories in all climate zones – hence colonizing Africa was necessary. The lowering of the Mediterranean would enable the production of immense amounts of electric power, guaranteeing the growth of industry. Vast tracts of land would be freed for agriculture – including the Sahara desert, which was to be irrigated with the help of three sea-sized man made lakes throughout Africa. The massive public works, envisioned to go on for more than a century, would relieve unemployment and the acquisition of new land would ease the pressure of overpopulation, which Sörgel thought were the fundamental causes of political unrest in Europe. Sörgel also believed the project's effect on the climate could only be beneficial. The Middle East, under the control of a consolidated Atlantropa, would be an additional energy source and a bulwark against the Yellow peril.

The publicity materials produced for Atlantropa by Sörgel and his supporters contain plans, maps, and scale models of several dams and new ports on the Mediterranean, views of the Gibraltar dam crowned by a 400-metre tower designed by Peter Behrens, projections of the growth of agricultural production, sketches for a pan-Atlantropan power grid, and even provisions for the protection of Venice as a cultural landmark. Concerns about climate change, earthquakes, attacks, and the fate of African culture are often ignored as being unimportant.

The project never gained substantial support despite its fantastic scale and eurocentric expansionism. Under the Nazi regime the plan was ridiculed as it was against the idea of a Eurasian German Empire. The Italians never supported the idea, as their cities were so dependent on the coastlines. After the Second World War interest was piqued as the allies sought to create closer bonds with Africa and combat communism, but the invention of nuclear power, the cost of rebuilding, and the end of colonialism left Atlantropa technologically and politically unnecessary, although the Atlantropa Institute remained in existence until 1960.