Elizabeth viewed the main Olympic Stadium from a platform at the top level of stands, and walked along a section of the 100-meter track area. She was accompanied by Sebastian Coe, a two-time Olympic 1,500-meter champion who heads London's organizing committee.

“She was very pleased to be standing on the finishing straight,” Coe said. “She was asking which point of the track she was standing at. I said, 'You're about 20 paces from winning the 100-meter final, ma'am.”'

Wearing a purple dress and hat, the queen got a look at where the royal box will be located in the 80,000-capacity stadium. She also planted the first of 4,000 trees to be put on the park site.

“Planting the tree today is the first step in the creation of a new green space that will reflect the traditions of great British parks and will create a fantastic backdrop for the Games,” Olympic Delivery Authority chairman John Armitt said.

Elizabeth is due to open the Olympics in 2012 when she will be celebrating her 60th year as queen. She opened the 1976 Olympics in Montreal as head of state of Canada.

The 2.5-square-kilometer (1-square-mile) Olympic Park also includes the velodrome, aquatics center, basketball arena and main media center, and is adjacent to the athletes' village.