Tumbling Weir
The 928th tallest dam in the world
The Tumbling Weir is a circular weir in the town of Ottery St. Mary, Devon, England, that allows water from a leat or man-made stream to reach the River Otter. It is apparently a rare design in that the water enters through a circular opening at the top that is surrounded by the stream. The water then cascades down several smaller rings until it enters a culvert, which leads into a tunnel under the nearby path before sluicing down to the river a few metres away.
Dam data from Wikidata (CC0) plus curated additions. Summary from Wikipedia (CC BY-SA).