Interesting premise. Infill is pretty common in cities where real estate is expensive. I’m not sure what the “tipping point” is but large chunks of the city of

Interesting premise. Infill is pretty common in cities where real estate is expensive. I’m not sure what the “tipping point” is but large chunks of the city of Boston are built on what was water. The neighborhood “Back Bay” is named quite literally. NYC likewise has large chunks of prime real estate built on artificial land. Manhattan’s Battery Park was once water. The motivation here does seem to have been economic. Singapore also is similarly growing out into the sea, though the motivation there is the lack of land in other directions, not merely price. The Aztec city of Tenochtitlan was similarly built in the middle of a lake on a foundation of floating grass islands called “chinampas.” Here the motivation was martial - the lake served as a moat for their imperial capital. Venice was built similarly to the Tenochtitlan on mostly a series of man-made islands, though the motivation seems to have been population growth. The Chinese today are building artificial islands in the South China Sea, the motivation here is martial/legalistic - expand the land territory and power projection to expand their claim to the sea.