The harmony and unity of a South Bronx street once so elite, it was nicknamed the “Irish Fifth Avenue”

They look like the kind of row houses that make Greenwich Village and the Upper West Side so picturesque—elegant stone facades, rounded archways, pops of stained glass, and cast iron railings on stoops and balconies. But this four-block span of loveliness, built between the 1860s and the 1890s, is part of the Mott Haven neighborhood of the South Bronx. Though it’s just across the Harlem River from Manhattan, Mott Haven is an enclave that still lives with its 1970s reputation of brokenness. Not many New Yorkers know of its remarkably well-kept Gilded Age houses whose lines, shapes, and colors create a rhythm of flow and beauty. All this harmony is centered around Alexander Avenue between 137th and 141st Streets. In the late 19th century, this stretch earned the nickname “the Irish Fifth Avenue” for the well-off second- and third-generation Irish immigrants who made their homes here. Alexander Avenue was also known as “Politicians’ Row” and “Doctors’ Row,” which can give you an idea of…