Duke Karl II became a monarch in the sovereign Duchy of Braunschweig created by the Congress of Vienna in 1815 at the age of 16. As part of his upbringing, he spent two years in Lausanne with his brother in 1820.
Due to his lavish lifestyle and political conflicts with the country estates, he made himself unpopular with the population and had to leave his country in 1830 as a result of an uprising. With the consent of the other monarchs of the German Confederation, he was replaced in 1831 by his brother Wilhelm as duke.
In 1870 Karl moved to Geneva because of the Franco-Prussian War, where he died on August 18, 1873 without direct descendants. In his will, he appointed the city of Geneva as the sole heir, whereby he required the construction of a tomb according to his own plans at a prominent location in Geneva. His brother Wilhelm reached an amicable agreement with Geneva on March 6, 1874, on the division of the inheritance, whereupon the city still had a sum of 24 million francs, which today is said to correspond to around 1 billion Swiss francs. After some discussion, the tomb was erected by the city of Geneva in the Jardin des Alpes in 1879 and inaugurated on October 14, 1879.