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From 9 February for two days his coffin rested in St. Mary Magdalene Church, Sandringham, before lying in state at Westminster Hall from 11 February. His funeral took place at St. George's Chapel, Windsor Castle, on the 15th. He was interred initially in the Royal Vault until he was transferred to the King George VI Memorial Chapel inside St. George's on 26 March 1969. In 2002, fifty years after his death, the remains of his widow, Queen Elizabeth The Queen Mother, and the ashes of his younger daughter Princess Margaret, who both died that year, were interred in the chapel alongside him.

What church did the King's funeral take place on the 15th?
Windsor Castle