Koch was also an outspoken supporter of Israel, willing to criticize anyone, including President Barack Obama, over decisions Koch thought could indicate any wavering of support for that nation.
In a WLIW television program "The Jews of New York," Koch spoke of his attachment to his faith.
"Jews have always thought that having someone elevated with his head above the grass was not good for the Jews. I never felt that way," he said. "I believe that you have to stand up."
Under his watch from 1978-89, the city climbed out of its financial crisis thanks to Koch's tough fiscal policies and razor-sharp budget cuts, and subway service improved enormously. But homelessness and AIDS soared through the 1980s, and critics charged that City Hall's responses were too little, too late.
Koch said in a 2009 interview with The New York Times that he had few regrets about his time in office but still felt guilt over a decision he made as mayor to close Sydenham Hospital in Harlem. The move saved $9 million, but Koch said in 2009 that it was wrong "because black doctors couldn't get into other hospitals" at the time.
"That was uncaring of me," he said. "They helped elect me, and then in my zeal to do the right thing I did something now that I regret."
His mark on the city has been set in steel: The Queensboro Bridge — connecting Manhattan to Queens and celebrated in the Simon and Garfunkel tune "The 59th Street Bridge Song (Feelin' Groovy)" — was renamed in Koch's honor in 2011.
Koch was a champion of gay rights, taking on the Roman Catholic Church and scores of political leaders.
A lifelong bachelor, Koch offered a typically blunt response to questions about his own sexuality: "My answer to questions on this subject is simply, 'F--- off.' There have to be some private matters left."