Mar-a-Lago is located in Palm Beach, Florida, which is in Palm Beach County. It is a resort and National Historic Landmark that was built between 1924 and 1927 for businesswoman and socialite Marjorie Merriweather Post. The property extends from the Atlantic Ocean to Lake Worth Lagoon, which forms part of the Atlantic Intracoastal Waterway. Mar-a-Lago is the second-largest mansion in the state of Florida and the 22nd largest mansion in the United States.