This is SO cool!

The Falkirk Wheel, named after the nearby town of Falkirk in central Scotland, is a rotating boat lift connecting the Forth and Clyde Canal with the Union Canal. The difference in the levels of the two canals at the wheel is 24 metres (79 ft), roughly equivalent to the height of an eight storey building.

The wheel, which has an overall diameter of 35 metres (110 ft), consists of two opposing arms which extend 15 metres beyond the central axle, and which take the shape of a Celtic-inspired, double-headed axe. Two sets of these axe-shaped arms are attached about 25 metres (82 ft) apart to a 3.5 metres (11 ft) diameter axle. Two diametrically opposed water-filled caissons, each with a capacity of 80,000 imperial gallons (360,000 l/96,000 US gal), are fitted between the ends of the arms.




These caissons always weigh the same whether or not they are carrying their combined capacity of 600 tonnes (590 LT/660 ST) of floating canal barges as, according to Archimedes' principle, floating objects displace their own weight in water, so when the boat enters, the amount of water leaving the caisson weighs exactly the same as the boat. This keeps the wheel balanced and so, despite its enormous mass, it rotates through 180° in five and a half minutes while using very little power. It takes just 22.5 kilowatts (30.2 hp) to power the electric motors, which consume just 1.5 kilowatt-hours (5.4 MJ) of energy in four minutes, roughly the same as boiling eight kettles of water.

The wheel is the only rotating boat lift of its kind in the world, and is regarded as an engineering landmark for Scotland. The United Kingdom has one other boat lift: the Anderton boat lift in Cheshire. The Falkirk Wheel is an improvement on the Anderton boat lift and makes use of the same original principle: two balanced tanks, one going up and the other going down, however, the rotational mechanism is entirely unique to the Falkirk Wheel.
H/T Not PC
(who has lots of other fascinating art/architecture stuff)