By focusing her attention on a small, seven-square-block enclave on Manhattan's East Side, Klein (author of Aline, the 1979 biography of Aline Bernstein, Thomas Wolfe's mentor and mistress) is able to present a kaleidoscopic survey of N.Y.C.'s (and America's) social and artistic life from the 1820's to the outbreak of WW II. Among the figures who play colorful roles in Klein's narrative are such little-known New Yorkers as Samuel Ruggles, the creator of the neighborhood that even in 1831 was remarkable for its gracious serenity--a quality that still pervades Gramercy Park. Much better known are American giants like Edwin Booth, Herman Melville and Eugene O'Neill; of slightly less-exalted stature are such ""originals"" as Carl Van Vechten, Elsie de Wolfe, and O. Henry, all of whom at one time or another made the area their Manhattan home. Klein's recounting of the Gramercy Park lives of Edwin Booth and William Sidney Porter (O. Henry) is especially successful, in large part because of the conflicts she finds in these lives. Both men were hounded by tragedy--Booth through his father's carousing and his brother's assassination of Lincoln, Porter through his own early imprisonment for embezzlement and his alcoholism. Less dramatic but very nearly as involving are the details of the lives of Edith Wharton, Nathanael West, and Ben Sonnenberg, three residents whose only probable point of agreement would be their common appreciation of Gramercy Park. Written in an anecdote-filled style that keeps the pages turning briskly, this charming and informative book should prove popular not only with Gothamites but also with readers intrigued by cultural history.