With the opening ceremony less than two weeks away, final preparations for the Olympics have taken London by storm.

In Trafalgar Square, a group of dancers delicately maneuvers on a rotating ladder. At the futuristic Millennium Bridge, red-suited acrobats bounce up and down like yo-yos, while others walk across the roof of London's glass-domed city hall. It's all a part of the Olympic celebration, even though the official kick-off won't happen until July 27. Between now and then, hundreds of workers are scrambling to get the city ready.

Inside the 560-acre Olympic Park in east London, a small army of workers is laying cables, installing seats and adding the last layers of sparkle and polish to Olympic venues. A sea of white tents, cranes, bulldozers, upturned tables and chairs, humming generators, television cables and rigging, and a maze of fences now obscure the view of the park.

Things may look a bit messy right now, London organizers say, but everything will be in place by the time the torch is lit next week. Organizers pride themselves on finishing their massive construction project ahead of time and on budget.

Among the final projects, crews must transport 5,000 tons of sand from a quarry south of London to Horse Guards Parade-the beach volleyball venue located only a stone's throw from the Prime Minister's Downing Street residence in central London. In the Docklands area, workers are transforming the ExCel conference and exhibition center into arenas for boxing, judo, table tennis, wrestling, fencing, taekwondo and weightlifting.

"The bump-in looks quite messy, but you leave this to the last stages," said James Bulley, director of venues for the Olympic organizing committee. "It's always the last thing you do in getting events ready. We want to work these venues right up to when the athletes are coming in so they look as good as possible."

Meanwhile, as athletes, officials and media from all over the world arrive, Heathrow Airport faces serious logistical challenges.

With the opening of Athlete's Village, Monday marks the first major wave of arrivals. Heathrow officials say athletes from 50 nations will touch down in what is being described as Britain's biggest peacetime transportation challenge. In all, the airport will handle some 236,955 passengers, breaking the previous daily record of 233,562 set in July 2011.

London has four other airports, but Heathrow is the only airport where participants can get their Olympic credentials, so it will handle the bulk of Olympic arrivals. To cope, Heathrow has enlisted some 1,000 volunteers to greet visitors. Volunteers are dressed in bright pink so they easily stand out.

Peter Nicholas, 59, from Camberley, south of London, will spend the next few weeks volunteering at the airport, happily working shifts that can start as early as 4:30 a.m.

"It's a once-in-the-lifetime experience," he said. "We're helping to make the games work."

Special teams are set to deal with oversized items like Olympic javelins, bikes and other sports equipment. Kenneth Andreasen, the head coach for the U.S. Olympic sailing team, says that his team must carry sails and other equipment on the plane. Officials at Heathrow are well aware that losing or breaking the bags of high-profile athletes could be a public relations disaster, and they are working with baggage handlers to ensure that doesn't happen.

"We have spent seven years preparing for the Games' challenge," said Nick Cole, head of Heathrow's Olympic operations. "Now we are putting that planning into action with thousands of extra staff and volunteers on hand to welcome the world to London."

About 10,490 athletes from 204 nations will participate in the games. America will send 530 athletes, many of whom are still in college. According to a list provided by the NCAA, 82 students enrolled in NCAA institutions will represent their country in sports ranging from fencing to field hockey.

Outside Heathrow, rows of Olympic VIP buses wait to whisk teams and coaches to the Athlete's Village. Official "Games Lanes" along the vital M-4 highway from Heathrow into central London have been set aside to transport Olympic officials, VIPs and athletes as quickly as possible.

The next matter of concern for Olympic officials as visitors arrive is security. The massive Olympic security operation includes RAF combat jets, surface-to-air missiles on rooftops and an aircraft carrier on the River Thames.

But officials already have been forced to adjust security measures thanks to failure by G4S, a private security firm, to recruit enough personnel to protect the venues. The blunder has forced the British government to bring in thousands of extra troops to guard the games.

International Olympic Committee President Jacques Rogge praised British organizers Monday for acting quickly and said the heavy security presence at the games will "definitely not spoil the fun."

Rogge said the issues have been handled well: "What counts is the flexibility of the organizing committee and the government when something comes up and I think they have been very flexible and very adaptive."

And flexibility will continue to be key when it comes to the one thing that the Olympic committee won't be able to control-London's weather.

For much of the summer, London has experienced relentless rain, and the conditions were again damp and gloomy on Monday for the arrival of athletes and the opening of Athlete's Village.

Rain could pose challenges for Olympic tennis at Wimbledon and track and field at the Olympic Stadium. Wimbledon has a retractable roof on Centre Court, but many matches will be scheduled on other, uncovered courts.

"That might need some rescheduling, but you know that Wimbledon has great experience in that," Rogge said, "Athletes are adaptive and they can cope with all conditions."

The Associated Press contributed to this report.