They stand proudly gazing across the Hudson River at the cliffs of New Jersey. Their brows are marked by ornamental pediments. Greek columns stand as sentries by their entrances and stone medallions bedeck their chests. They are seven graceful relics of Beaux Arts New York, townhouses built more than 100 years ago for a new class of industrialists, actors and scientists -- many from abroad -- who made their fortunes in the United States and shaped...