She suffered a stroke Monday, her spokeswoman said. A British government source said she died at the Ritz Hotel in London.
Thatcher’s funeral will be at St. Paul’s Cathedral, with full military honors, followed by a private cremation, the British prime minister’s office announced.
Thatcher served from 1975 to 1990 as leader of the Conservative Party. She was called the “Iron Lady” for her personal and political toughness.
She retired from public life after a stroke in 2002 and suffered several strokes after that.
She made few public appearances in her final months, missing a reception marking her 85th birthday hosted by Prime Minister David Cameron in October 2010. She also skipped the July 2011 unveiling of a statue honoring her old friend Ronald Reagan in London.
In December 2012, she was hospitalized after a procedure to remove a growth in her bladder.