The rise of the German-based supermarket has been almost stratospheric in recent years - becoming one of the most popular supermarkets in the UK.
But there is a strange and at times dark history behind the business which was run by two brothers after the second world war.
Fortunes, strange personalities and even a kidnapping have shaped the business and made the brothers, Karl and Theo Albrecht the two richest men in Germany.
But how did it go from a small store in war-torn Germany to the giant battling the 'big four' supermarkets for retail supremacy?
Wales Online have looked into the strange history of the chain.
The company was established by the German brothers after the Second World War.
They took over the business started by their mother Anna who, in 1913, opened a small grocery store in the West German suburb of Essen.
The siblings frequently helped out in the shop as young boys and were later conscripted into the army, with Karl ending up wounded and captured on the eastern front.
Theo fought in Rommel’s Afrika Korps before becoming a POW in Italy in 1945.
They returned home after the fighting stopped to find Essen decimated by bombing - their family's shop, however, miraculously remained intact.
Taking it over they found great success under the banner Albrecht KG, their budget retail model proving a huge hit with Germans who'd learned to live on a shoestring during the recent conflict.
Sticklers for efficiency and keeping their overheads low - shunning advertising and stocking only the surefire bare essentials, the Albrechts quickly expanded the business into a network of small shops.
By 1950 they owned 13 stores in the Ruhr Valley region, upping that to 300 stores across Germany by 1960 and turning over millions each year.
However, at around the same time Karl and Theo fell out after an argument over whether or not their stores should stock cigarettes - as a result, they decided to split their empire right down the middle.
Theo would go on to head all the stores in northern Germany - renaming the business Albrecht-Diskont Nord, while Karl concentrated on the south of the country with Albrecht-Diskont Süd.
Low key to the point of invisibility, the pair uncharacteristically found themselves thrust into the spotlight in December 1971 when Theo was kidnapped at gunpoint by a convicted housebreaker known as 'Diamond' Paul Kron.
Incredibly, the criminal's lawyer Heinz Joachim Ollenburg was also in on the act and the pair kept Theo prisoner in a cupboard in Dusseldorf for 17 days while the ransom amount (seven million Deutschmarks or £1.5m) was thrashed out.
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The cash ended up being dropped off at the designated rendezvous point at the side of a main road by the Bishop of Essen, who was acting as a go-between, with Karl Albrecht contributing half the money.
The kidnappers didn't get away with it though - they were later arrested having fled to Mexico and sentenced to eight-and-a-half years inside.
Only half the money was ever retrieved and the two kidnappers, who both died in 2017, took to their graves the truth about what happen to the rest.
Theo, who later unsuccessfully attempted to get round the taxman by having the ransom written off as a business expense, would become a virtual recluse.
He never allowed his photo to be taken and would even travel to work in an armoured car, taking a different route each day.
When the Albrechts came to the UK to take on giants like Tesco and Sainsburys they initially made little impact.
Now established as Aldi - short for Albrecht Discount - they boasted just 2% market share, the same as its rival fellow German firm Lidl which followed soon after.
By 2017 though it was biting at Morrisons' heels for a place in the Big Four of British supermarkets, having already taken over Co-op with a 7.5% market share.
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It was also doing well in America where, in 1976, Karl’s company opened its first store in Iowa City.
Aldi now has more than 10,000 locations in 18 countries, including 1,659 in the US as of last summer.
In later life Karl and Theo were said to spend much of their time living on a remote island they owned in the North Sea, where they supposedly played golf and furthered their hobbies of collecting vintage typewriters and growing exotic orchids.
Theo Albrecht died, aged 88, in July 2010. At the time of his passing he was Germany's second richest man, after his brother.
Karl, who had amassed a fortune of about $29 billion, would pass away six years later - one of the the wealthiest men on the planet.
The Albrechts' original store in Essen is still open today.
