landlords and government agencies rolled out a slew of security measures, as Vanity Fair writer Bryan Burrough outlines in his book on the radical underground Days of Rage. Those measures included requiring ID to enter police facilities, having doormen at skyscrapers call to confirm people's appointments, and installing electric door openers and surveillance cameras.

Already in 1970, in the aftermath of the bombing of a bathroom in NYPD headquarters, the New York Times was taking stock of efforts to ramp up security to combat terrorism. In an editorial, the paper concluded, "Nothing and no one can be made safe from a man determined to explode an infernal machine in a public building."

The NYPD disagrees with this stance, as became apparent again following the al-Qaeda truck bombing of the WorldTrade Center in 1993, which killed six. Worried that a similar attack might be carried out near the New York Stock Exchange, the police in 1996 closed the intersection of Wall Street and Broadway to vehicular traffic. A bomb threat in 1998 prompted the closure of the sidewalks around the stock exchange every night from 6 p.m. to 8 a.m.

In the aftermath of 9/11, these sidewalk closures became permanent, and the roadblocks were extended to seven intersections around the stock exchange, prompting one of the first widely publicized conflicts over access to public space related to the security takeover. Joseph Vassallo, owner of a parking garage with an entrance behind the blockade at Exchange Place and William Street, sued the city in 2004, claiming that his business had