Luxembourg is a small, landlocked country in Western Europe, bordered by Belgium, France, and Germany. Its capital, Luxembourg City, is one of the four official capitals of the European Union and the seat of the European Court of Justice. The country is divided into two main regions: the Oesling in the north, which forms part of the Ardennes mountains and is characterized by forests and valleys, and the Gutland in the south, which is more fertile and contains the majority of the population and the capital. Luxembourg is the world's only remaining sovereign grand duchy, headed by a Grand Duke. Despite its small size, it has one of the highest GDP per capita in the world. The country is trilingual, with Luxembourgish, French, and German all serving as official languages. Historically, its strategic location and massive fortifications earned its capital the nickname 'Gibraltar of the North.'