In this study we focus on the possible impact of 9/11 on tall and trophy office buildings for market behavior that could influence value. We find little evidence of any significant departure from general market trends for tall buildings or most Ïtrophyó property, yet there appear to be some effects on returns and values for a small subset of truly famous buildings in both New York and Chicago. Using an additional survey aimed at property managers we find little evidence of tenant flight away from tall buildings, or dense urban areas, yet property managers do expect significant design changes in the future as a result of 9/11 and most have tightened security procedures.