September 1st is Disaster Prevention Day in Japan. Exactly 100 years have passed since the Great Kanto Earthquake, which occurred on September 1st, 1923. In order to prevent flood damage when rivers overflow due to heavy rain, Tokyo has built facilities called regulating ponds that can temporarily store increased water underground. There are 28 control areas for the 12 rivers that flow through Tokyo. In Kasukabe City, Saitama Prefecture, a flood control facility (Metropolitan Area Outer Underground Discharge Channel: MAOUDC) is being built to reduce flood damage in the metropolitan area. This facility is sometimes called the "underground temple" because the ceiling is supported by 59 gigantic pillars that are 18 meters high and weigh 500 tons, giving it a temple-like appearance. Tours of the building are also available to the general public.