a more natural way. For Marine City, Kikutake proposed a city that would float free in the ocean and would be free of ties to a particular nation and therefore free from the threat of war. The artificial ground of the city would house agriculture, industry and entertainment and the residential towers would descend into the ocean to a depth of 200 metres. The city itself was not tied to the land and was free to float across the ocean and grow organically like an organism. Once it became too aged for habitation it would sink itself. Ocean City was a combination of both Tower-shaped City and Marine City. It consisted of two rings that were tangent to one another, with housing on the inner ring and production on the outer one. Administrative buildings were found at the tangent point. The population would have been rigidly controlled at an upper limit of 500,000. Kikutake envisaged that the city would expand by multiplying itself as though it was undergoing cell division. This enforced the Metabolist idea that the expansion of cities could be a biological process. Space City In his essay "Space City", Kurokawa introduced four projects: Neo-Tokyo Plan, Wall City, Agricultural City and Mushroom-shaped house. In contrast to Tange's linear Tokyo City Bay Project, Kurokawa's Neo-Tokyo Plan proposed that Tokyo be decentralised and organised into cruciform patterns. He arranged Bamboo-shaped Cities along these cruciforms but unlike Kikutake he kept the city towers lower than 31 metres to conform with Tokyo's building code (these height limits were not revised until 1968). The Wall City considered the problem of the ever-expanding distance between the home and the workplace. He proposed a wall-shaped city that could extend indefinitely. Dwellings would be on one side of the wall and workplaces on the other. The wall itself would contain transportation and services. Surviving the Ise Bay Typhoon in 1959 inspired Kurokawa to design the Agricultural City. It consisted of a grid-like city supported on 4 metre stilts above the ground. The 500 metres square city sat on concrete slab that placed industry and infrastructure above agriculture and was an attempt to combine rural land and the city into one entity. He envisaged that his Mushroom Houses would sprout through the slab of Agriculture City. These houses were shrouded in a mushroom-like cap that was neither wall nor roof that enclosed a tea room and a