Kansai International Airport, located on an artificial island in Osaka Bay, Japan, has long dealt with a unique engineering challenge: subsidence, or gradual sinking of the ground beneath it. The airport was built in the 1990s to address noise complaints from nearby communities and to reduce conflicts over air traffic. Designed by renowned Italian architect Renzo Piano, the airport opened on September 4, 1994, and withstood the 1995 Kobe earthquake, proving the structural soundness of the project. However, the long-term stability of the island has remained a concern. The subsidence issue arises from the soft marine sediments and clay beneath the airport. These materials compress under the weight of the airport's structures, causing the ground to sink slowly over time. Engineers had anticipated some settling, but the extent and duration of the subsidence have exceeded initial predictions. The second artificial island, constructed later for expansion, is in an even more delicate condition, showing that even with improved construction techniques, the geology remains unpredictable. To combat the sinking, airport authorities use a system of hydraulic jacks to gradually lift the airport structures, counteracting the annual subsidence. This maintenance plan includes adjustments every three years and the reinforcement of dikes to protect against rising sea levels. A sophisticated network of sensors and hydraulic systems monitors the movement of the airport's foundations, which rest on over a million piles driven deep into the seabed. These piles are designed to resist earthquakes but cannot entirely prevent the slow compression of the underlying clay. Despite economic challenges, including unmet expectations about Japan's continued growth and the airport’s role as a major international hub, Kansai International Airport remains operational and busy. It serves tens of millions of passengers annually and continues to host major events, such as the Osaka World Expo. A new terminal was inaugurated in 2023, highlighting the airport's ongoing importance and its ability to adapt to both engineering and economic challenges.