Monaco, officially the Principality of Monaco, is a federal city-state and microstate in Western Europe, located on the French Riviera near the Italian region of Liguria. It is bordered to the north, east, and west by France, and to the south by the Mediterranean Sea. The principality has a population of 38,682 people, 9,486 of whom are Monégasque nationals; it is widely regarded as one of the most expensive and wealthy places on the planet. The official language is French, but Monégasque, Italian, and English are spoken and understood by a sizable population. It is the world's second smallest sovereign state, after Vatican City, with an area of 2.1 km2. It is the world's most heavily populated sovereign state, with 19,009 people per square kilometer. Monaco has a land boundary of 5.47 kilometers and the world's shortest coastline of 3.83 kilometers, with a range ranging from 1,700 to 349 meters. The state's highest point is 161 meters above sea level, reached through a narrow path known as Chemin des Révoires on the slopes of Mont Agel in the Les Révoires ward. The principality is about 15 kilometers from the Italian border. Larvotto/Bas Moulins, with a population of 5,443, is the most populous ward. Monaco's land mass has grown by 20% as a result of land reclamation. It was just 1.974 km2 in size in 2005. Prince Albert II is the head of state of the principality, which is ruled by a kind of constitutional monarchy. Despite being a constitutional king, Prince Albert II wields enormous political power; the Minister of State is the head of government. The officeholder may be a Monégasque or a French resident, and the monarch consults with the French government before making a decision. Since 1297, the House of Grimaldi has dominated Monaco with only minor interruptions. The Franco-Monégasque Treaty of 1861 recognized the state's sovereignty, and Monaco became a full United Nations voting member in 1993. Monaco's defense is the responsibility of France, despite its independence and separate foreign policy. Monaco does, however, maintain two small military units. The founding of the state's first casino, the Monte Carlo Casino, as well as a railway link to Paris, sparked economic growth in the late 19th century. Monaco's mild climate, beautiful scenery, and gambling facilities have all led to the principality's reputation as a wealthy tourist destination. Monaco has become a major banking center in recent years, and it has attempted to diversify its economy by focusing on services and tiny, high-value-added, non-polluting industries. The state has no income tax and low business taxes, earning it a reputation as a tax haven. With real estate values approaching €100,000 per square metre in 2018, over 30% of the population is a millionaire.