The Bridge Piers on the Old Sagami River is the ruins of a bridge that appeared in a paddy field following the Great Kanto Earthquake of September 1, 1923 and the aftershocks in January of the following year. According to the historian Numata Yorisuke, the bridge was built in 1198 by Inage Shigenari, a chief vassal of Minamoto no Yoritomo, as a memorial for his late wife, and the site was designated as a National Historic Site in 1926. Subsequent surveys also uncovered new earth retaining remains on the north side of the piers, and this part was additionally designated in February 2007. In addition, traces of liquefaction caused by the earthquake have been confirmed, and the area was designated as a Natural Monument of Japan in 2013 as a historical legacy that preserves the seismic conditions of the Great Kanto Earthquake. It was the first liquefaction in the country to be a nationally designated natural monument. Currently, the 10 piers have been backfilled into the ground for preservation, and their replicas are placed above them in the pond, with monuments and explanation boards.