When Andrew Carnegie purchased a swath of property on Fifth Avenue at 90th Street, it was considered the boonies – too far uptown from the acceptable social center. But, of course, where Carnegie goes, others follow. On this tour, we’ll see Carnegie’s house – now the Cooper Hewitt Museum, as well as other turn-of-the-century mansions built by new-money industrialists of the early 20th century, with a stop at the Warburg Mansion, now the Jewish Museum, designed by the “lacy architect,” CPH Gilbert.