addressed as Highness. Those members of the royal family who weren't children or grandchildren of a king, i.e., the princes du sang, were entitled to be addressed as "Most Serene Highness" (son altesse sérénissime). The simple style of "Highness" (altesse) was claimed by the princes étrangers and the princes légitimés. In fact, these formal styles were seldom employed in conversation, since the princes du sang used unique styles (e.g. Mademoiselle, Monsieur le Prince), while the ducal peers, led by the proud Duc de Saint-Simon, avoided conceding the altesse to the princes étrangers and bâtards royaux, prompting nobles of lesser rank to do likewise. The reigning Prince of Monaco, Albert II, is addressed as His Serene Highness. His wife, children and younger sister, Princess Stéphanie, are also referred to as Serene Highness. His elder sister, Princess Caroline, was also styled Her Serene Highness prior to her 1999 marriage, but is styled Royal Highness since then, even during the period when she was officially "The Hereditary Princess of Monaco" as heiress presumptive to the throne. A particularly well known holder of this style of address was Grace Kelly, who was titled, HSH The Princess of Monaco. In French, both male and female versions are Son Altesse Sérénissime (S.A.S.), which translates, literally, as "His/Her Most Serene Highness". Italy In the Republic of Venice (697-1797), also called "the Most Serene Republic" , "la Serenìsima Repùblega" in Venetian ( "la Serenissima Repubblica" in Italian ), the Doge was known as Serenissimus ("Most Serene") as was the Duke of Mantua. Children of the Savoy kings and crown princes of Italy were entitled to the treatment of Royal Highness, but more remote male-line descendants were Serene Highnesses by right (although often the style of Royal Highness was granted to them ad personam, e.g., the Dukes of Aosta or the Dukes of Genoa). The mediatised House of Thurn and Taxis, entitled to the Serene Highness treatment in the German Empire, has a non-dynastic cadet branch, the Dukes di Castel Duino, which obtained naturalization in Italy in 1923. When incorporated into the Italian nobility, their use of the Serene Highness style was authorised by the Crown. San Marino San Marino is styled as the Most Serene Republic. Poland In the First Republic of Poland (1569-1795), also called "the Most Serene Republic of Poland" (Najjaśniejsza Rzeczpospolita Polska), His/Her Serene Reigning Majesty (SRM) was a style used by the reigning monarchs.