The Shimizu Corporation's Ocean Spiral Project

Ocean Spiral has been dreamt up by the Japanese Shimizu Corporation. The top of the globe stands above the surface of the ocean, and running through the centre is a tower to add strength. It will provide space for homes, offices and even an amusement park for 5,000 underwater residents. No part of the project has yet been built, and the total cost is thought to exceed $26 billion.