The enormous fortunes generated by robber barons in the post-Civil War Era led to an unprecedented level of luxurious living for wealthy Americans.

[6] He is credited with popularizing Thousand Island dressing at the Waldorf-Astoria Hotel, where he instructed the maître d', Oscar Tschirky, to include it on the menu.

The enormous castle was intended as a gift for his wife, Louise Kehrer Boldt, but when she died suddenly on January 7, 1904, in Manhattan, at the age of 42, construction was halted.

Towards the end of his life, he commissioned architect Francis T. Underhill to build him a Swiss-chalet-style mansion, "La Manzanita," in Montecito, Santa Barbara, California.

[citation needed] Boldt once owned Nikola Tesla's Wardenclyffe Tower property, receiving it as payment for a debt.

[14][e] During his lifetime, Boldt was a frequent donor to Cornell University, the American Red Cross, many local hospitals and built a library at Alexandria Bay, New York.

[5] Boldt's will equally divided US$15 million between his son and daughter, with a request to his children that they continue to financially support the charities he had donated to in the past.