REGARDING ALL THE POSTS ABOUT RAPTURE:
Rapture is located at 63° 2' N, 29° 55' W, which places it at about two hundred sixty-nine miles west of Iceland's capital, Reykjavik. According to the National Geophysical Data Center, the depth at this point would be around 1500m, that's almost a mile. Rapture's size is rumored to be around the size of Manhattan, New York, New York. Rapture began build in 1946 and finished only in 5 years in 1951. Given all this information, and seen Rapture in-game, I, myself being a civil engineering student for 3 years, can say that it is a fantastic world albeit very unrealistic. Obviously realism isn't something to pick on when talking about a game like this, however to answer the question: "How was rapture built?", we'll have to. First of all, visible sunlight disappears only 200m under, so the light seen outside the windows, can only be light installations. The whole city is built in Art Deco style, however, the forms of the buildings are completely inappropriate for holding off the huge amount of pressure from the ocean mass. Since the buildings are dry, and therefore can be seen as hollow shells, they would just collapse under the pressure. And in 1946, there were no means of building underwater whatsoever, and even today, it's practically impossible. For comparison, Hydropolis in Dubai is only 20m underwater, and the costs for building are 700 million dollars. Which brings us to the next point: money. No man, or country has enough money to build Rapture, the technologies don't exist even today. The expenses for materials, and transport are immense, and the means of transporting material to the building site on the sea bed are even more so. Also you can't build on the surface of the ocean to sink it afterward, as it will sink immediately on it's own, and I doubt a stable country could build Rapture using it's whole budget, even if there were materials that could withstand this kind of pressure. So to sum it up, Rapture is a beautiful and creative work of art, but there is no way it could exist in reality. Rapture... can't be built.