Organizers have staged the final test events ahead of the London Olympic Games.

An estimated 75-thousand spectators have descended on the Olympic park in London, for five test events ahead of the Games. Saturday marks the first time the main stadium in the heart of the Olympic Park will be open to the public for an athletic competition.

Organizers say about 40-thousand people are expected to attend the official opening of the 80,000 seats Olympic Stadium on Saturday evening. The Olympics run from July 27 to August 12 while the Paralympics take place from August 29 to September 9.

A general view of the Olympic Stadium in London. More than 40,000 spectators watched as a cascade of white balloons was released to officially open London's Olympic stadium on Saturday, exactly 2,012 hours before the Games begin.?