The Falkirk Wheel is the only rotating boat lift of its kind in the world.
It links the Forth and Clyde Canal with the Union Canal in Scotland.
Boats once climbed a staircase of 11 locks. The trip took nearly a whole day.
In 1933, those locks were dismantled.
A structure 115 feet (35 meters) tall now stands in their place, as high as eight double-decker buses stacked one on another.
Two gondolas, closed troughs for the boats, raise or lower them 79 feet (24 meters).
How does it work?
The wheel makes a half turn in five and a half minutes.
The energy used is roughly equivalent to boiling eight kettles of water.
Balance does the rest.
When a boat enters, it displaces water that weighs exactly the same as the boat, so the gondola stays level no matter the load.
The motors do not lift the weight.
They only turn a wheel that is already balanced.
In 2002, Queen Elizabeth II opened it, and it became the heart of the link between the two canals.
Since then, it has been an engineering landmark and a stop for visitors.
Those 79 feet?
A full day of locks fits into one quiet half turn.
The old route swallowed hours.
The wheel almost turns itself.
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