Even the Princely House of Monaco can be traced back to the Duchy of Saxe-Gotha-Altenburg.
Ernest the Pious’ daughter, Elisabeth Dorothea became the Landgravine of Hesse-Darmstadt through marriage. The blood line was inherited as far as Amalie the Hereditary Princess of Baden. Amalie’s son, Karl, became the Grand Duke of Baden and his granddaughter Marie became the first Princess of Monaco from Duke Ernest the Pious’ blood line.
Marie the Princess of Monaco is Prince Albert II of Monaco’s great-great-grandmother.