Lower City Mills

Lower City Mills is part of a cluster of former watermill buildings, collectively known as City Mills,[2] in Perth, Scotland. It was given Category A listed status in 1965 by Scotland's Ancient Monument Division (now Historic Environment Scotland).[3] Milling has taken place at the location since the 14th century.
en.wikipedia.org/wiki/Lower_City_Mills

Using the power of moving water to drive a mill wheel is an ancient invention of the human spirit of discovery, the origins of which can be traced back to times long past. Thanks to such a construction, human or animal muscle power could be easily replaced by the power of the natural elements through a watercourse - natural or artificially created - in order to grind grain into corn or press oil from fruit, for example.There are essentially two different ways of driving watermills:* Either the flowing water simply hits the blades of the water wheel from below to set it in motion; or
* the water is guided above the wheel - usually through a so-called "mill channel" - and falls onto the blades; this type of construction is more efficient due to natural gravity.