The Queen Elizabeth Memorial Committee, which will select the winner, said it would judge all submissions against a value for money criteria.
The late queen’s former private secretary Lord Janvrin, chairman of the committee, said: “The memorial must be – simply – a beautiful place, somewhere to visit with family and friends, to enjoy and to reflect on an extraordinary life.”
“We are looking for teams who thoroughly understand and connect with our ambitions for the project,” he added.
Pat McFadden, chancellor of the Duchy of Lancaster, said: “This national memorial will provide a permanent tribute to the late queen’s legacy, offering space for reflection as well as celebration.”
The two-stage competition has opened, with the winners to be announced in the summer.