A section of St James’s Park visible from Buckingham Palace will be re-landscaped for the national memorial, with a budget previously said to be between £23m and £46m.
The anti-monarchy campaign group Republic has called for the Royal Family to pay for the memorial rather than the government.
“They can pay for their own statue,” the group’s chief executive Graham Smith said.
The winning design for the memorial, chosen from a shortlist of five concepts, will feature a bridge with a balustrade made of glass, inspired by the shape of the late queen’s wedding tiara.
There will also be a statue of her and Prince Philip, to whom she was married for 73 years until his death in 2021, a Prince Philip Gate and new gardens.
The final designs will be put to the King and the prime minister next year.