1.   In advance of the speech, the Kennedy School became a virtual fortress.

2.   Officials are exploring ways to turn the White House and all federal buildings into virtual fortresses.

3.   Set back from the street, with a recessed entrance, it was a virtual fortress.

4.   The extra police and military personnel add another layer of security to an area that was a virtual fortress before the explosion in downtown Atlanta.

5.   Armed with sophisticated automatic weapons, traffickers have turned the favelas into virtual fortresses and terrorize residents.

6.   Armed with sophisticated automatic weapons smuggled into Brazil, traffickers have turned the favelas into virtual fortresses and terrorize residents.

7.   Police have turned the casino into a virtual fortress, erecting a steel fence around it.

8.   The clubhouse is a virtual fortress in a residential neighborhood.

9.   Elite privately-owned schools have tightened security, becoming virtual fortresses while nervous parents have begun escorting children to classes.

10.   Elite privately-run schools have tightened security, becoming virtual fortresses while jittery parents have begun escorting childen to classes.