For sheer 4th-of-July exuberance, neither Kelly nor Donen ever made a better film than On the Town. It was based on a stage musical by Betty Comden and Adolphe Green with music by Leonard Bernstein, and inspired by the Jerome Robbins’ ballet, Fancy Free. Robbins choreographed the 1944 stage musical, as he had the earlier ballet version. Arthur Freed saw it, took an option on it, and finally adapted it to the screen, prompting his invaluable assistant, Roger Edens (who produced the film) to write an entirely new set of songs in conjuction with Comden and Green.
Freed said of Roger Edens: “He’s one of the very great contributors to any musical he has worked on. His feeling in laying out a musical, his arrangements, his general showmanship are rare. He’s great to work with. I can’t tell you how much he’s helped me”.
As associate producer on the film, Edens realized his chance of making musicals without over-elaborate production numbers. “Intimate musical is the only way to get true entertainment. People are not entertained by chorus lines anymore. It’s also less expensive and more rewarding to concentrate to the principals. On the Town was a very happy wedding of creative spirits. Freed turned us loose on it, and Kelly is a worker: he loves to work. The whole lay-out of the picture and all the numbers, including that wonderful one on the top of the Empire State, were unforgettably exciting for all of us to put together!”.
In On the Town, Kelly was at last the director, and it reflects beautifully in his performance. What is sometimes his insufferable excellence is here transformed into that particular American genius for spontaneity. New York, that Himalayan of cities, with its sky-high scrapers, its unique exhilarating restlessness (if you stand still, the houses seem to move by), is the perfect background for Kelly and his troupe of performer: Betty Garrett chasing shy Sinatra, Kelly in pursuit of Vera-Ellen, and Ann Miller after Jules Munshin. The best thing in the film takes place in the anthropological section of New York’s Natural History Museum, where Miller adopts cave-woman tactics for her pre-historical dance number. […] On the Town broke completely with the Hollywood convention of what a musical should be and should look like, and proved that the dance numbers could be effectively staged in actual locations. For Kelly and Donen, too, it was breakthrough.

John Kobal, Gotta Sing Gotta Dance – A Pictorial History of Film Musical, Hamlyn, London-New York-Sydney-Toronto 1971