Princess Alexandra of Saxe-Altenburg, (July 8, 1830 – July 6, 1911) was the fifth daughter of Joseph, Duke of Saxe-Altenburg and Duchess Amelia of Württemberg, daughter of Duke Ludwig of Württemberg and Princess Henrietta of Nassau-Weilburg
Princess Alexandra of Saxe-Altenburg is an ancestress of the British, Greek, Romanian, Serbian, and Spanish Royal Families through her elder daughter Olga. She was a paternal first cousin of Princess Pauline of Württemberg, as well as her maternal second cousin.
Via that link, those six people (Friedrich II Eugene, Duke of Württemberg, Princess Friederike of Brandenburg-Schwedt, Ernst Friedrich III, Duke of Saxe-Hildburghausen, Princess Ernestine of Saxe-Weimar, Charles II, Grand Duke of Mecklenburg-Strelitz and Princess Friederike of Hesse-Darmstadt), are ancestors of almost every single royal family in Europe (exceptions being Liechtenstein and Monaco).

Princess Alexandra of Saxe-Altenburg
Early life
Alexandra’s parents were married on 24 April 1817, at Kirchheim unter Teck. Alexandra had five sisters: Marie, Pauline, Henriette, Elisabeth, and Luise.
Marriage and issue
In the summer of 1846, she met Grand Duke Constantine Nikolayevich of Russia when he visited Altenburg. He was the second son of Emperor Nicholas I of Russia, and Empress Alexandra Feodorovna, née Princess Charlotte of Prussia, the eldest surviving daughter and fourth child of Frederick Wilhelm III, King of Prussia, and Duchess Louise of Mecklenburg-Strelitz, and a sister of Friedrich Wilhelm IV, King of Prussia and of Wilhelm I, German Emperor and King of Prussia.
Grand Duke Constantine stayed for a few days at Alexandra’s father’s castle. His visit there had been arranged by Alexandra’s aunt, Grand Duchess Elena Pavlovna, who had been born Princess Charlotte of Württemberg. Elena and Alexandra’s mother were both descended from Friedrich II Eugene, Duke of Württemberg.
Grand Duchess Elena was married to Grand Duke Michael Pavlovich, the younger brother of Emperor Nicholas I. Grand Duchess Elena Pavlovna was therefore Constantine’s aunt by marriage and Alexandra’s aunt by birth.
Elena was a strong influence over Constantine, who admired her intellect and progressive views. She had literary interests and was musical, founding the St Petersburg Conservatoire, and the young Konstantin often spent time at Elena’s home and salon in St Petersburg.
Constantine was intellectual and liberal, whereas Alexandra was conservative and rather high spirited. Although their temperaments differed, they both shared an interest in music, and enjoyed playing duets at the piano.

Princess Alexandra of Saxe-Altenburg
Constantine was captivated by Alexandra’s youthful beauty: she being tall, slender and attractive. He quickly became besotted, and was eager to marry her “I don’t know what is happening to me. It is as if I am a completely new person.
Just one thought moves me, just one image fills my eyes: forever and only she, my angel, my universe. I really do think I’m in love. However, what can it mean? I’ve only know her just a few hours and I’m already up to my ears in Passion”. She was only sixteen and Konstantin nineteen; they were engaged but had to wait two more years before they could finally marry.
Alexandra arrived in Russia on October 12, 1847, and was greeted by much fanfare and popular celebration, with jubilant crowds lining the streets and balconies. It was said that Alexandra looked so much like her fiance’s sister, the Grand Duchess Alexandra Nikolayevna, who died in childbirth, that her prospective mother-in-law burst into tears at their first meeting.
In February 1848, Alexandra converted to Russian Orthodoxy, taking the name of Grand Duchess Alexandra Iosifovna, which reflected her father’s name Joseph (unlike many princesses she took a patronymic, choosing to reflect her parentage rather than the usual religious or dynastic associations which was also possible because Iosif was a common name in Russia).
Alexandra and Constantine were married in the Winter Palace in St Petersburg, on September 11, 1848. Constantine received the Marble Palace in St Petersburg as a wedding gift from his parents. Strelna on the Gulf of Finland, which Constantine inherited when aged four, was the wedded couple’s country retreat.

Grand Duke Constantine Nikolayevich of Russia
Grand Duke Constantine was the paternal great-great-grandfather of King Charles III of the United Kingdom, since his daughter Olga married George I of the Hellenes, whose son Prince Andrew married Princess Alice of Battenberg, and they became the parents of Prince Philip, Duke of Edinburgh, Charles’ father. Through Constantine I of Greece, another son of Olga and George I, Konstantin is also the paternal great-great-grandfather of Queen Sofía of Spain, mother of King Felipe VI of Spain.
The lively Grand Duchess Alexandra Iosifovna took a particular interest in the grounds at Strelna, establishing a free school of gardening, where she taught classes herself. There were also educational toys for the children: a wooden mast and trampoline for gymnastics, and the transplanted cabin of one of Constantine’s frigates.
A year after their marriage Constantine inherited the Pavlovsk Palace, situated 19 miles to the south of St Petersburg, from his uncle Grand Duke Michael Pavlovich. The public was admitted to the fine park in its grounds. The Grand-Ducal family supported an impressive concert hall situated at Pavlovsk station, which proved popular with the middle classes, and attracted names such as Johann Strauss II, Franz Liszt, and Hector Berlioz.
Alexandra and Constantine later acquired the palace of Oreanda in Crimea, which had originally been built by Tsarina Alexandra Feodorovna and left to her second son for his retirement.