From the record
“Armour III House is a historic mansion in Lake Bluff, Illinois, USA. Armour III, grandson of Armour and Company founder Philip D.”
Wikipedia article Philip D. Armour III House, CC BY-SA 4.0.
One of 98 National Register listings published here for Lake County · listed in 1996 · category: Building.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service