Question: What member of nobility does Dalmeny House and Barnbougle Castle have in common?
Context: Andreas von Österreich, Margrave of Burgau, also known as Andrew of Austria (15 June 1558 at Březnice Castle in Březnice, Bohemia – 12 November 1600 in Rome) was a cardinal, Bishop of Constance and of Brixen.  He belonged to the Austrian nobility, descending from its ruling dynasty, the House of Habsburg. The earliest recorded family member was Otto von Rohr (c. 1350-1427), the German Bishop of Havelberg from 1401 to 1427.  The Von Rohrs are Swedish House of Nobility noble family number 807 and Finnish House of Nobility noble family number 85. Baron Louis Gerard De Geer of Finspång (18 July 181824 September 1896) was a Swedish statesman and writer.  De Geer was born at Finspång Castle in Risinge parish.  He was a lawyer, and in 1855 became president of the Göta hovrätt, or lord justice for the appellate court of Götaland.  From 7 April 1858 to 3 June 1870 he was Prime Minister for Justice and again from 11 May 1875 to 20 March 1876.  As a member of the nobility he took part in the Swedish Riksdag of the Estates from 1851 onwards.  From 1867 to 1878 he was the member for Stockholm in the first chamber in the New Riksdag, and introduced and passed many useful reforms. The House of Leyen ("von der Leyen") is an ancient German family of high nobility, the origin of which can be traced to the middle of the 10th century, which had estates on the Moselle.  Originally the family was named de Petra or by its castle in Gondorf (Cunthereve).  Since the 14th century it has called itself von der Leyen.  Its members had the hereditary office of sénéchal in the bishopric of Trier.  They also had Adendorf near Bonn, Leiningen on the Hunsrück, the Lordship of Arenfels and St. Ingbert. The House of Hatzfeld, also spelled Hatzfeldt, is a prominent German Countly and Princely family.  They belonged to high nobility originally from Hesse.  The family is first mentioned in 1138 and has its ancestral seat in Hatzfeld.  In 1418 the family inherited Wildenburg Castle near Friesenhagen, a Lordship with Imperial immediacy, from the Lords of Wildenburg. Claus Bille (ca. 1490 – 4 January 1558 at Lyngsgård, Scania) was a Danish statesman.  He was a major estate owner, knight (the highest rank of Danish nobility), fief lord of Båhus Castle and a member of both the Norwegian and the Danish Councils of the Realm.  He was an important participant in the Stockholm Bloodbath, when he together with Søren Norby arrested the Swedish nobility.  He was a first cousin of Eske Bille, and the Bille family became the most politically powerful noble family of Denmark during his lifetime. The Marquess of Trazegnies d'Ittre "Markies van Trazegnies" or "marquis de Trazegnies" is a title of the Belgian Nobility.  The title has been held for centuries by the noble house of Trazegnies ("Maison de Trazegnies").  They hold private residence in the Castle of Corroy-le-Château.  The house of Trazegnies is divided into two families: "de Trazegnies" and "de Trazegnies d'Itrre". Barnbougle Castle is a much-altered tower house on the southern shore of the Firth of Forth, between Cramond and Queensferry, and within the parish of Dalmeny.  It lies within the Earl of Rosebery's estate, just northwest of Dalmeny House.  Although its history goes back to the 13th century, the present castle is the result of rebuilding in 1881 by the 5th Earl of Rosebery, who served as Prime Minister from 1894–1895. The House of Guttenberg is a prominent Franconian family which traces its origins back to 1149 with a Gundeloh v. Blassenberg (Plassenberg).  Though, the first mention in a document is dated 1158.  The name Guttenberg is derived from Guttenberg and was adopted by a Heinrich von Blassenberg around 1310.  The Plassenberg family were ministeriales of the Counts of Andechs (later the dukes of Andechs-Meranien) and used as their seat the Plassenburg of Kulmbach.  The castle of Guttenberg remains the main seat of the family.  The family currently consists of two branches.  The elder branch, von und zu Guttenberg and the younger Steinhausen branch.  In 1700 the family rose from "Reichsritter" (Imperial Knights) to "Reichsfreiherr" (Barons of the Holy Roman Empire).  After the Holy Roman Empire dissolved, they were made "Freiherr" (barons) of Bavaria (1814 & 1817).  According to historian Werner Wagenhöfer, the Guttenberg family is the most researched family of the low nobility in Franconia along with the Seckendorff and Bibra families. Dalmeny House is a Gothic revival mansion located in an estate close to Dalmeny on the Firth of Forth, to the north-west of Edinburgh, Scotland.  It was designed by William Wilkins, and completed in 1817.  Dalmeny House is the home of the Earl and Countess of Rosebery.  The house was the first in Scotland to be built in the Tudor Revival style.  It provided more comfortable accommodation than the former ancestral residence, Barnbougle Castle, which still stands close by.  Dalmeny today remains a private house, although it is open to the public during the summer months.  The house is protected as a category A listed building, while the grounds are included in the Inventory of Gardens and Designed Landscapes in Scotland.
Answer: Earl