[Elgin marbles British Museum]Richard Baker / In Pictures via Getty Images Images) * The EU and Britain will begin talks on a post-Brexit free trade deal next month. * The thorny issues are aplenty with one European minister saying negotiators will "rip each other apart." * It has emerged that in those talks, the EU will ask Boris Johnson to give ancient marbles back to Greece. * Greece argues that the Parthenon marbles, taken from Athens by British diplomat Lord Elgin over 200 years ago, were removed unlawfully and should be returned. * The classic Greek structures are displayed in the British Museum in London. * Visit Business Insider's homepage for more stories. The European Union will demand that Britain gives ancient marbles back to Greece as part of a post-Brexit trade deal. Greece has long argued that the Parthenon marbles — or Elgin marbles — were unlawfully removed from the Parthenon temple in Athens in the early 19th century by Lord Elgin, a British diplomat at the time. SEE THE REST OF THE STORY AT BUSINESS INSIDERNOW WATCH: A 45-year-long study discovered trends in successful hyper-intelligent children SEE ALSO: * Michael Jackson's Neverland Ranch has been pulled off the market after failing to sell for almost 5 years. Look inside the 2,700-acre property that was once asking $100 million. * Jeff Bezos just pledged to spend $10 billion to fight climate change. Here's how the richest person in the world makes and spends his billions. * Retiring early doesn't mean you'll stop making money — here's how a retired millennial made more than $60,000 in passive income in one year