Ushigome-mon Gate was located between the Ushigome-bori and Iida-bori Moats. A weir was constructed under Ushigome Gate in order to protect the earthen bridge that dammed the water in Ushigome-bori Moat and control the water level. When JR Iidabashi Station’s platform was relocated in 2017, remnants of stone paving believed to comprise a portion of the weir was discovered for the first time anywhere in the outer moat area. Photographs from the Meiji period contain images of the weir’s outfall and the sections of stone paving uncovered at the site are thought to have comprised a portion of the aqueduct located immediately in front of the outfall. Currently, the section of stone paving discovered is 2017 is preserved in its original location directly under the train platform. A portion of the platform’s surface has been modified in order to express the scope of the area that was covered by the stone paving. In addition, a portion of the paving removed from the site is on display in the plaza in front of the Station. It enables visitors to get a sense of the weir’s size. Unfortunately, no documents or records that describe the weir’s structure have been discovered. A similar type of structure known as the Sekiguchi Weir, however, which was constructed during the same period and transported water into the city from the Kanda River, provides us with some insights about weir technology and design. Located in present-day Bunkyo Ward’s Sekiguchi district, the arrangement of stone material used to construct the Sekiguchi Weir’s channel resembles that of the stone paving discovered along the outer moat in 2017. Also from the platform you can see the current waterway connecting the moats.