This is part of the Kobe Earthquake Memorial Park that preserves a portion of the seawall and pier as it was after the Great Hanshin-Awaji Earthquake of January 17, 1995. The magnitude 7.3 earthquake damaged 116 kilometers of the Kobe Port shoreline and affected 239 berths. While these materials have been left to essentially rust and erode in place, quite a bit of engineering was performed to brace everything underwater to keep it from toppling over into the bay. The fact that the preserved section has been left to rust away means that it isn't really a perfect image of how things looked on January 18, 1995. The rusted metal currently contributes to a stark post-apocalyptic vibe, but as it decays over time, it will look more like abandoned waterfront that simply has not been maintained.