Software will be watching and listening.
Recent leaps in technology have paired highly sophisticated software with street surveillance cameras to create digital security guards with intelligence-gathering skills.
"It is the first time it is being done on such a scale at an international level," Greek police spokesman Col.-Lefteris Ikonomou said.
The system -- developed by a consortium led by San Diego-based Science Applications International Corp., or SAIC -- cost $312 million and took up a sizable chunk of Athens' record $1.5 billion security budget.
It gathers images and audio from an electronic web of more than 1,000 high-resolution and infrared cameras, 12 patrol boats, 4,000 vehicles, nine helicopters, a sensor-laden blimp and four mobile command centers.
Spoken words collected by the cameras with speech-recognition software are transcribed into text that is then searched for patterns along with other electronic communications entering and leaving the area -- including e-mail and image files.
The system covers all of greater Athens, nine ports, airports and all other Olympic cities.
The software used for surveillance camera recordings "can distinguish the sound of a flat tire from an explosion or a gunshot and inform the user at the command center of the incident," said Dionysios Dendrinos, general manager of One Siemens in Greece, one of the companies in the consortium.
"It listens, reads and watches," Dominic Johnson, Autonomy's chief marketing officer, said of his company's software. Then it synthesizes. Beyond Greek and English, the software understands Arabic, Farsi and all major European languages, Johnson said.
There'll also be sniffing going on.
A network of sensors designed to detect chemical agents has also been deployed near Olympic venues and around the capital, including on the security blimp.
Advanced technology also was used to make the Olympic credentials, which use holograms. All cardholder information, including a person's photo and passport number, are printed on a very thin film designed to make the cards impossible to forge.
But not everyone is happy at authorities' computer-aided eyes and ears.
"Although the state's right to take all necessary measures that it deems necessary is recognized, there is fear that these measures will have a negative impact on basic human rights," six human rights groups said in a protest letter to the Greek Parliament in July.