One of Britain's most famous aqueducts is being spruced up and being stripped of all graffiti in time for its 200th birthday celebration in a project costing £1.5m.
The aqueduct carries the Llangollen canal over the River Dee
The 1,000 foot long Pontcysyllte Aqueduct near Llangollen in north Wales is the oldest operational cast iron aqueduct in the world.
Built by Thomas Telford, it was opened in 1805 - the year Nelson won the Battle of Trafalgar.
Described by the novelist Sir Walter Scott, as the finest work of art he had ever seen, the aqueduct carries the Llangollen canal on 19 slender arches, 126 feet above the Dee Valley.
On Monday the latest clean-up which will involve scaffolding being strung along the length of the cast iron aqueduct trough was ceremonially launched.
And next Monday and Tuesday all 12,000 cubic metres - around 12,000 bath tubs - of water will be completely drained away.
It is the first time the structure - also the world's highest aqueduct - has been overhauled in five years.
Work on the clean-up will take around 20 weeks and involve up to 40 workers.
It has been programmed over the winter by British Waterways to keep the disruption to the canal boaters who regularly used it to a minimum.
The nearby valley of Trevor Basin will also be improved to include new paths, landscaping, seating and artwork.
The first stone of Thomas Telford's Pontcysyllte Aqueduct was laid on 25 July 1795 and it officially opened on 26 November 1805, at a cost of £45,000.
Preparations are well advanced for the 200th birthday celebrations with various events planned through the year.
British Waterways, the agency responsible for the canal and river network throughout Wales, England and Scotland, has also spent months building up an old library of the aqueduct.
"We want local people to play their part in celebrating this living piece of history by rummaging through attics and garages to dig out any old photographs or artefacts," said Nicola Lewis-Smith from Wales & Border Counties Development.