Prepared by the NYPD's counter-terrorism bureau, the report, "Engineering Security: Protective Design for High Risk Buildings," assigns the city's buildings to either low-, medium- or high-risk categories, and provides recommendations for mitigating these risks. Although it does not identify any specific buildings as high-risk, the report says they're structures which present several risk factors at once.

These factors range from location to structural design. They include: high-visibility, nationally recognizable architectural designs; proximity to other high-risk buildings or to major infrastructure; a lack of controlled access; the inability to withstand specific blast pressures at certain distances; maximum occupancy of more than 10,000 people or height greater than 800 feet; and key financial or government tenants.

During a presentation at NYPD headquarters on Wednesday, police commissioner Raymond Kelly told building owners that they could access a self-scoring system to determine their own properties' risk levels. Most buildings in the city fall within the low-risk category, the report states.