A Long Island Mansion by the N.Y. Public Library’s Designer

About 25 miles east of Midtown Manhattan stands Old Westbury, N.Y., a Long Island village where wealthy families have built opulent mansions in country club settings since the middle of the 19th century. One of bucolic enclaves most prestigious estates belonged to American architect Thomas Hastings, who designed and built the imposing residence at 10 Hastings Road for himself. Set on nearly 20 acres, the $18.9 million property is currently pending subdivision to accommodate a total…