Giuliani was a great mayor because he had the most important gift of great leadership: the ability to cut through all the crap and identify a single, simple, but overpoweringly important objective--and to remain focused on it despite every distraction and provocation:

Every mayor of NYC understood that crime-and-grime were important, and some tried to address it. Giuliani, alone, understood the underlying issue: the perception that the city was ungovernable and out of control. The average NYer or visitor was unlikely to be murdered, beaten, robbed, raped or mugged on any given day. But, they were very likely to encounter other signs of lawlessness: turnstile-jumpers, three-card monte players, low-level drug dealers, radio-blasters, litterers, aggressive panhandling, etc. Giuliani went after those "quality of life" crimes aggressively, and demanded that everyone around him stay focused on them, not just the police.

Not surprisingly, Giuliani's focus resulted not only in the city becoming cleaner and more civil, but in a large number of arrests for felonies, and a lower crime rate. Turned out that a large percentage of people ticketed or arrested for "minor" crimes had outstanding warrants for felonies. In one case, a guy who brutally murdered an Upper East Side woman in her cleaning store was nabbed because he had a warrant for turnstile-jumping. In another case: a young woman was attacked and almost killed on a busy street corner by a brick-wielding, deranged homeless man. Giuliani immediately recognized that it was exactly the kind of crime people fear most: a senseless, unprovoked attack that can't be guarded against. He assigned 80 detectives to track the perp down and was on radio and TV three times a day, giving NYers updates. They got the guy in a few days. Giuliani's big effort wouldn't have prevented another senseless attack. But, he proved to NYers that he cared about, and was outraged by, the crime. He built confidence.

My personal experience: In the late '90's, I walked all the way from Penn Station to 99th Street on the East Side to visit an aunt in the hospital. The streets were incredibly clean, I didn't encounter one panhandler, and I was amazed at how quiet it was.

His courage and leadership on 9/11 and afterward were magnificent. All of America, not just New York, owes him a debt of gratitude.