Grand duchy
country or territory whose official head of state or ruler is a monarch bearing the title of grand duke or grand duchess / From Wikipedia, the free encyclopedia
A grand duchy is a country whose head of state is a Grand Duke or Grand Duchess.
The only grand duchy in existence today is Luxembourg. Luxembourg became a grand duchy in 1815 when the Netherlands became an independent kingdom, and King William I of the Netherlands was made Grand Duke of Luxembourg. In 1890, the two countries separated. William III of the Netherlands had no male heir, so in the Netherlands he was succeeded by Queen Wilhelmina but Luxembourg followed Salic law, which meant only a man could rule. The present Grand Duke of Luxembourg is Henri.
However there are other houses of Europe that style themselves as Grand Dukes even if not wholly recognised by the rest of society.
The independent republics of Finland and Lithuania, and the Dutch province Limburg (Duchy of Limburg) have been Grand Duchies at certain times in their history.