See inside Eagle's Nest, the 42-acre New York Vanderbilt estate where a Gilded Age heir built his sprawling mansion

The entrance to Eagle's Nest. Gabbi Shaw/Business Insider The Suffolk County Vanderbilt Museum is a must-see for any "Gilded Age" fan. The museum was once the estate of William K. Vanderbilt II, the son of William and Alva Vanderbilt. Alva is the inspiration behind Bertha Russell, who is played by Carrie Coon on the show. Can you hear "The Last Great American Dynasty" playing in the distance? There are many historical mansions on Long Island, but only one was once owned by the legendary Van...