As the twin towers fell, all eyes turned toward the Sears Tower, AON Center and the John Hancock Building and wondered if they’d be hit next.

Residents and tenants of Chicago’s 10 trophy buildings wondered if they’d made the mistake of their lives by living among the clouds. But as the dust settled, Chicago moved ahead and created new security for Chicago’s skyscrapers.

Living somewhere at the top of America’s second most famous skyline was a destination address for many in Chicago until 9/11.

“Lots of concerns of how are we going to get out of here if something happens,” says Ed Stein, a Water Tower Place resident.

Sitting ducks. That’s how many trophy building residents and tenants felt. If something happened and firemen were called.

“They would know to go to the 34th floor, but once they got there, they wouldn’t have any idea of what to do,” says Bob Ladner, president of Systems Development Integration.

So the city of Chicago passed an ordinance requiring all buildings of about eight stories or higher, and there are about 1,400 of them, to create “The Plan.”

“The Plan is a security plan and an emergency evacuation plan that also describes what happens during an emergency whether that’s fire, earthquake or some kind of disaster,” says Ladner.

Chicago’s 10 trophy towers, which are at least 78 stories tall, had to actually file their plans with the city’s Office of Emergency Communications. But even these detailed requirements weren’t enough to settle some nerves.

“One of the problems we had to solve is communication. To let people know what to do if some catastrophe took place in the building,” Stein says.

At Water Tower Place, the residents quickly formed a security committee and spent $150,000 installing a wireless one-way communication system called an “Enunciator,” that allows someone at ground level to speak to one unit or the whole building at once.

The residents took other security steps. Building employees, contractors and housekeepers have security tags and photo badges. Designated floor captains will assist all residents in an emergency. And the building is making a video to show residents how to get out fast.

“We’ve also printed out a card that has instructions on what to do in case of any emergency,” Stein says.

All this planning doesn’t come cheap.

“A building could spend $350,000 to $500,000 to comply with the ordinance,” Ladner says.

And after spending all that, a trophy building might pay another $1 million to insure their newly secure building.

“Security in a building is important, but from an insurance standpoint, it’s what kind of fire protection is involved in the building. Is there an enunciator system? Arethere sprinklers? Are there emergency evacuator plans?” says Mark McLellan, president of Condominium Insurance Specialists of America.

And with all this, will lives be saved?

“You hate to see what happens,” Ladner says.

But for residents and tenants, it’s at least bought peace of mind.

According to the city’s Office of Emergency Communications, all 10 trophy buildings have complied with the city’s new security ordinance as have more than 90 percent of buildings over 80 feet tall.