At Radio City Music Hall, guards check tourists' purses for weapons before the Rockettes' Christmas Spectacular. In Times Square, new cameras stare down at shoppers.
In rail stations, travelers are bombarded with messages warning them to be on the lookout for suspicious activity. There are poison-gas sensors, radiation detectors and automatic license plate readers.
The Woolworth Building no longer allows tourists. Visitors to the Statue of Liberty must go through two airport-style security checkpoints. Police conduct occasional spot checks of subway passengers, setting up a table in stations and searching travelers' bags at random.