"Obviously there's been some knee-jerk reaction to get out of high-rise towers and out of so-called target-type buildings," Levine says. "But for finance, marketing and advertising, people need to be in a hub. Those individuals will always need to maintain a presence in Manhattan, and you just can't afford to put up low-rise buildings in Manhattan--land is too expensive."

And building sizes in Manhattan are unlikely to change going forward, Levine says. "People seem to be very comfortable with the typical Sixth Avenue, 50-to-60-story office building." And it is that size building that developers are geared up for. "When you build a building that is not the norm, hoisting methods, craning, etc., becomes more difficult."

Insurance, Levine says, is off the table as a design-factor, at least for the near term. "At this point, the carriers are all indicating they don't have terrorism insurance anymore, which is a matter for government concern." He adds that the creation of federal reinsurance programs that sprung from the devastation caused by Hurricane Hugo in 1989 "should be used as a model going forward for use with terrorism events."