"As you can see," intoned Assistant Chief Henderson of the Eden Department of Public Health and Safety, "the blast doors that were designed into the basic structure of the city did their job very well. They activated within two seconds of the laser strike and sealed off the damaged section, preventing further loss of life and property. Without those blast doors, we would not be able to stand right here at this moment. This entire building would have been reduced to the outside atmospheric pressure."

Laura and the other two city council members who had gone on the tour with her were standing on the sixty-eighth floor of the MarsTrans building looking downward through the thick plexiglass windows. Around them rose countless other high-rise buildings, stretching upward into the red Martian sky. The high rise was the staple of life on Mars. People lived in them, worked in them, did business in them. A Martian city was nothing more than a compact collection of tall buildings that were located in a grid pattern of streets. The street level was where people moved from one building to another. All streets were enclosed by a steel and plexiglass roof thirty meters above the ground, and by plexiglass walls on the sides. This kept the air pressure inside, where it belonged, and the thin Martian atmosphere outside, where it belonged. The buildings did not actually touch each other but they were all connected to the street level complex making Eden, in effect, one giant, interconnected, airtight structure that was home to more than twelve million people. Then entire city was kept at standard Earth sea-level air pressure by means of a system of huge fusion powered machines that extracted the traces of oxygen and nitrogen from the thin Martian atmosphere and pumped it inside. This system of pressurization and air supply was what made human life on Mars possible, but it was a system that depended upon the airtight integrity of the city remaining intact.