The nation’s 1,700 stadiums and arenas are host to an alarming array of potential dangers, from rogue fans to suicide bombers. Here’s a sampling of the latest technologies to make them and you safer. Video-cam systems hooked up to metal detectors

[a] placed throughout the stadium detect suspicious quantities of metal and wirelessly alert guards. Biobriefcases carried by agents in the stands or detectors suspended from rafters

[B] sniff out pathogens like anthrax. Pop-up steel pipes

[c] installed near main entrances stop would-be truck bombers cold. And for Super Bowl like events, SWAT teams located on roofs use surface-to-air missile systems

[d] to shoot down any aircraft that have penetrated no-fly zones.