The sight of thousands of passengers in the long lines at Heathrow Airport, JFK, and LAX, snaking through the arrival halls or waiting patiently outdoors in rain slickers on August 10 produced a familiar kind of dread mixed with acceptance: Since September 11, 2001, our world has irrevocably changed. In assessing the implications of the attacks on the World Trade Center and the Pentagon, we find that—besides the discussions and plans for the affected sites and their memorials, and our new awareness of the elevation of architecture in the popular consciousness—the aftermath of those events has provoked spirited debate and sometimes transformation in the built world. Five years later, we ask, have we in fact progressed toward safer, healthier spaces?

To judge from the expressions on the faces of the waiting public in the airports, not much. Despite massive investment in airport security, including computerized baggage screening, various metal and trace explosive detectors, surveillance and perimeter intrusion systems, we still have no effective way of pinpointing liquid, peroxide-based explosives in our airports. So-called “puffer” technology, which emits bursts of air to find explosive traces on clothing, comes at a high price and takes up more precious space. Nor do we have guarantees that terrorists would not find other ways of slipping through the permeable borders that airline terminals, not to mention rail centers and ports, represent.