From the 1940s to the mid-1960s, on several evenings a week, thousands of Irish and Irish Americans flocked from miles around to the huge, bustling dance halls -- the Intercolonial, the Hibernian, Winslow Hall, the Dudley Street Opera House, the Rose Croix -- that dotted Boston's Dudley Square. For the city's Irish population, the Roxbury neighborhood, with its ballrooms and thriving shopping district, was a vital center of social and cultural life,...