The Queen is visiting the Wimbledon tennis championships for the first time in 33 years.
She is watching Britain's number one Andy Murray in action on Centre Court against Finland's Jarkko Nieminen.
Security has been stepped up and police will be visible around the court.
On her last visit on 1 July 1977, Virginia Wade won the ladies' singles championship - Britain's only singles' title in 33 years.
Upon her arrival the monarch was met by the Duke of Kent, who is president of the All England Club, as well as chairman Tim Phillips, vice-chairman Philip Brook and chief executive Ian Ritchie.
The Queen toured the grounds of the All England Club, walking past Aorangi Terrace - better known as Murray Mount or Henman Hill.
Large crowds lined the St Mary's Walk avenue ahead of the Queen's visit.
Players past and present, including Martina Navratilova and Billie Jean King and current champions Serena Williams and Roger Federer, met the Queen in the members' enclosure ahead of her arrival in the royal box on Centre Court.
And former champion Wade met the Queen again.
Federer said it had been a "big honour" to meet the monarch.
"After 33 years there is huge happiness that she should visit this year for the fans. I'm just so glad I got a chance to meet her," he said.
And record-breaking former Wimbledon champion Martina Navratilova said the monarch was "lovely".
The group who met the Queen included Venus Williams, Caroline Wozniacki, Jelena Jankovic, Rafael Nadal, Novak Djokovic and Andy Roddick.
Some of the players were invited to attend a lunch with the Queen where the menu included salmon, honey marinated chicken and the Wimbledon staple of strawberries and cream.
Some ball boys, ball girls and club officials also met her.
She then moved on to watch 23-year-old Murray in his bid for a place in the third round.
