From watercolour painting to restoration projects in Transylvania, Charles has had seven decades to develop a wide range of hobbies and interests.
His passion for saving the planet and organic farming -- once mocked as cranky -- is now seen as well ahead of his time.
But a tendency to lobby his personal views on subjects such as contemporary architecture has prompted questions over his judgement.
- Architecture -
In the 1980s, Charles mounted a crusade against "ugly" modern architecture, decrying a proposed extension to the National Gallery on Trafalgar Square in London as a "monstrous carbuncle". The planned design was scrapped.
Despite mockery, he put his philosophy into practice by backing construction of a model village called Poundbury on his land in Dorset, in southwest England, in the early 1990s.
The housing development, built in a neo-classical Georgian style, has been derided by some critics as derivative and soulless but it has proved popular with buyers.
He also helped redevelop a deprived area, Nansledan, near Newquay, in Cornwall, with colourful environmentally friendly housing and local amenities.
- Environment and farming -
He created an entirely organic garden and farm at his Highgrove Estate in Gloucestershire, western England.
He also launched the Duchy Originals organic food and drink range, now run by the upmarket supermarket chain Waitrose, featuring produce from British organic farmers working in a sustainable way.
A keen gardener, in an interview in 1986, he revealed his habit of talking to his plants, to widespread mockery.
"We have to reduce emissions urgently and take action to tackle the carbon already in the atmosphere, including from coal-fired power stations," he said.
He also spoke about his Aston Martin car which has been converted to run on biofuel made from surplus English white wine and whey from cheese manufacturing.
- Hunting and polo -
He also played polo until forced to retire in 2015 by a series of injuries.
He reportedly met his now wife Camilla at a match in the 1970s.
- Painting and books -
At an exhibition of his watercolours in London in 2022, he wrote that he found the art form "one of the most relaxing and therapeutic exercises I know".
"I find it transports me into another dimension which, quite literally, refreshes parts of the soul which other activities can't reach," he admitted.
Some seasoned art critics, however, have said their worth only came from having his name attached.
"They are not awful," sniffed The Guardian's Jonathan Jones in 2016. "They are merely ordinary -- and obviously amateur. He looks like what he is, a hobby artist."
Charles has written a number of books, including "The Old Man of Lochnagar" for children, about an old man who lives in a cave in the cliffs under a mountain overlooking the royal estate Balmoral, northeast Scotland.
Charles supports traditional arts and crafts, including through the Scotland-based NGO Turquoise Mountain that he founded with the British former politician Rory Stewart and Afghanistan's ex-president Hamid Karzai, which helps artisans in Afghanistan and other countries.
- Romania -
Charles has bought and restored several buildings in Romania's Transylvania, using traditional methods and furnishings.
Charles likes to boast that he is a distant relative of the 15th-century prince known as Vlad the Impaler via his Transylvanian great-great-great grandmother.
He told the Romanian president during a visit in 2017 that this gave him "at least a small stake" in the country.
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© Agence France-Presse
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