This article is about the hotel operator in Vienna, Austria. For other uses, see Imperial Hotel (disambiguation). The Hotel Imperial, also known as Imperial, Wien or simply The Imperial, is a five-star luxury hotel in Vienna, Austria. It is located at Kärntner Ring on the Ringstraße. The Imperial was acquired by Compagnia Italiana Grandi Alberghi (CIGA) after Prince Karim Aga Khan acquired the company in 1985 and began expanding its presence"which was purely Italian up to that time"into Spain and Austria. In 1994, the Starwood Hotels and Resorts took over CIGA and transformed it into its brand, The Luxury Collection, an assemblage of historic and venerable hotels in Europe that includes the Imperial. The building was designed by architect Arnold Zenetti and built under the direction of Heinrich Adam in 1863. Initially, it was planned as a city palace ( Stadtpalais) of Duke Philipp of Württemberg (1838-1917) and his spouse Duchess Marie Therese (1845-1927), née Archduchess of Austria, and its original name was Palais Württemberg. However, the Duke and the Duchess did not like their new home very much and, after having moved there in 1866, sold it only five years later. For the Universal Exhibition it was converted into a hotel in 1873. In 1928, two stories were added. But the original architecture is still very much in evidence and is an integral part of the luxurious atmosphere. The hotel's famous guests are too numerous to list. Dignitaries and royalty from around the world stay at the Imperial. It has had some infamous guests as well. Adolf Hitler, who worked at the hotel as a day laborer during his youthful period as a virtual tramp in Vienna, returned as an honored guest following the 1938 Anschluss. Also, Benito Mussolini stayed at the hotel during World War II but was shepherded through the back door on Sept. 13, 1943 following his spectacular rescue by German paratroopers in Unternehmen Eiche ( Operation Oak). Simon Wiesenthal, a survivor of the Nazi death camps who dedicated his life to documenting the crimes of the Holocaust, celebrated his 90th birthday at the Imperial Hotel. Today, The Imperial is, perhaps, Vienna's most exclusive five-star hotel. Guests of state typically stay at the hotel, such as the Emperor and Empress of Japan on their visit in 2002. A speciality of the house is the Imperial Tart or Imperial Torte as its called, which is a chocolate truffle, supposedly based on a secret recipe that is said to have been created by an apprentice cook who fashioned it when Emperor Franz Joseph opened the Hotel in 1873. The confection comes in either a plain pinewood box or a cardboard box (for shipments), each containing a single torte or group of small tortes. Tortes vary in size, from ones that are the size of an individually wrapped candy to others that are the size of a small cake (approximately six inches or fifteen centimeters). A complementary torte box is provided to each guest room and additional boxes can be ordered from the hotel for shipment. Nowadays, torte boxes are sold alongside other Imperial products, such as teas leaves and coffee beans (labelled "Imperial Teas and Coffee") and other varieties of chocolate confections. The Imperial ships its products worldwide, as the chocolates maintain freshness for two months.