The London Olympics has presented costly logistical and infrastructure challenges and has created the biggest peacetime security operation in the country's history, costing an estimated $877 million.
The British military has taken high-profile measures, from deploying over 17,000 soldiers inside and outside of London during the games to placing surface-to-air missile batteries atop residential buildings.
With so much emphasis on security, entering Olympic venues may make spectators feel like they are going through an airport check point. Just as airport security restricts certain items, the London Organizing Committee for the Olympic Games has listed a range of things that are prohibited or restricted.
Restricted items — those that "may disrupt competition, obstruct the view of other spectators or create a safety hazard" — may be confiscated.
The committee suggests that spectators bring as little with them as possible, but in most cases spectators are allowed to bring one medium, soft-sided bag into venues that can fit underneath a seat or on a lap. The more a spectator brings, the longer it will take to pass through security.
So what are some of the prohibited and restricted items in 2012 Olympic venues? Although most of the items — weapons, alcohol, drugs, fireworks, liquids, spray paint and pets — are obvious, but some may surprise you.
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Football fans play vuvuzelas, an item banned in Olympic staidums.
One of the most memorable items from the 2010 FIFA World Cup was the vuvuzela — a plastic horn that lent the South Africa event a characteristic "buzz."
During the London games, noisemakers, including vuvuzelas, air horns, hunting horns, klaxons, drums and whistles are restricted. Wembley Stadium is also prohibiting football rattles, trumpets, clappers and other musical instruments.
Although noise can be a nuisance, light devices, such as strobes and laser pointers, are completely prohibited since their use have the potential to directly influence the competition.
2. Personal wireless access points and 3G hubs
Private mobile WiFi hotspots, which allow wireless devices to connect to the Internet, are restricted. Although use of tablets and smartphones is allowed in the venues, these devices cannot be used as wireless access points. Because London's wireless system is likely to be strained during major events, speculation about this ban has focused on an attempt to reduce overall bandwidth use.
3. Flags of non-participating countries
Flags of non-participating countries are also restricted. Some 204 National Olympic Committees are represented, including 196 independent countries.
Some participants, such as the Cook Islands and Puerto Rico, are territories of larger countries but compete under their own flags. Non-participating flags are allowed if they are "under the umbrella of a participating country," such as the flag of England or Wales, which are under the umbrella of Britain.
Although most countries are participating, a few notable ones stand out, such as South Sudan (flag pictured), which declared independence from Sudan in July 2011 but has yet to form an Olympic committee.
This has forced marathon runner Guor Marial to compete as an independent rather than under the Sudanese flag. Another country not participating is the disputed territory of Western Sahara. Taiwan will compete under "Chinese Taipei," which has a flag created specifically for the Olympics.
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Look at that hat! It clearly wouldn't be allowed into any Olympic stadium.
4. Oversized hats
Just over a year ago, big hats were all the craze in London, during the wedding of Prince William and Kate Middleton. The Olympics, however, have restricted "oversized hats," which are likely to obstruct the view of other spectators.
According to the committee's guidelines, Olympic staff can help spectators determine what constitutes an "oversized hat." If your headgear is determined to be too large, it will be permanently confiscated.
5. 'Ambush marketing' materials
Also restricted are "any objects or clothing bearing political statements or overt commercial identification intended for ambush marketing."
Ambush marketing is a strategy where companies place their branding in the midst of a public, sponsored event without paying a sponsorship fee, seeking to create an association with that event without authorization. Although ambush marketing can take many forms, the restriction seeks to remove any unauthorized companies from associating their brand with the Games.
6. Bicycles and skateboards
Although the athletes on the playing surface may be sporting them, that doesn't mean spectators should feel free to bring bicycles, folding bikes, roller-skates or skateboards into venues. They're too large to fit under a seat or on a lap, and would certainly be a nuisance to others.
Biking is popular in London, so an announced ban on non-folding bicycles on trains during the Olympics was lifted after only 36 hours.
7. Walkie-talkies, phone jammers and radio scanners
If you're looking to communicate with your friends wirelessly during the Olympics, stay away from walkie-talkies. They're banned. Phone jammers, which disable mobile phones from connecting to base stations, and a ban on radio scanners are likely the result of terrorism concerns since they could be used to intercept communications of security personnel.
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Umbrellas are a common sight in London. But unless you're Mary Poppins during the opening ceremony, big ones are not allowed in Olympic venues.
8. Large golf-style umbrellas
Reports of poor weather for the Olympics have been dampening spirits, but viewers will be even more depressed when they have no way of protecting themselves from the rain. Commonly used by spectators at golf tournaments, these oversized umbrellas could disrupt views of others. Instead pull on a pair of "wellies" and pack a slicker.
9. Balls, rackets, Frisbee or other projectiles
Imagine you are a beach volleyball player and it is the final set, and you have a chance to make it to the podium when a Frisbee floats by. Distracted, you miss the last block, and the game is over.
The Olympic committee wants to prevent this scenario, or worse, from happening. Anything that can be thrown, shot or launched at the athletic event cannot be taken in by a spectator. It is up to the discretion of the security guards to determine what is a "projectile."
10. Excessive amounts of food
Anyone who has ever been to the movies, a professional sporting event, play or concert knows it's cheaper to eat before going and the Olympics are no exception.
At the Games, a 300 ml bottle of Heneken lager is £4.20 ($6.50), and a plate of curry and rice is £8.50 ($13.15). Bottles of water can be purchased for £1.60 ($2.50).
These high prices will likely encourage people to bring their own food, but the amount will be restricted by the Olympics, who want their partners, like Coca-Cola, McDonald's and Cadbury, to profit.