Monaco, officially the Principality of Monaco is a sovereign city-state, country, and microstate on the French Riviera in Western Europe. France borders the country on three sides while the other side borders the Mediterranean Sea.

Monaco has an area of 0.780 sq mi, making it the second-smallest country in the world after the Vatican. Its population was about 38,400 based on the last census of 2016. With 19,009 inhabitants per km�, it is the most densely-populated sovereign state in the world. Monaco has a land border of 3.40 mi, a coastline of 2.38 mi, and a width that varies between 1,859 and 382 yd. The highest point in the country is a narrow pathway named Chemin des R�voires on the slopes of Mont Agel, in the Les R�voires Ward, which is 528 feet above sea level. Monaco's most populous Quartier is Monte Carlo and the most populous Ward is Larvotto/Bas Moulins. Through land reclamation, Monaco's land mass has expanded by 20 percent; in 2005, it had an area of only 0.762 sq mi. Monaco is known as a playground for the rich and famous, due to its tax laws. In 2014, it was noted about 30% of the population was made up of millionaires.

Monaco is a principality governed under a form of constitutional monarchy, with Prince Albert II as head of state. Although Prince Albert II is a constitutional monarch, he wields immense political power. The House of Grimaldi has ruled Monaco, with brief interruptions, since 1297. The official language is French, but Mon�gasque, Italian, and English are widely spoken and understood. The state's sovereignty was officially recognized by the Franco-Monegasque Treaty of 1861, with Monaco becoming a full United Nations voting member in 1993. Despite Monaco's independence and separate foreign policy, its defense is the responsibility of France. However, Monaco does maintain two small military units.

Economic development was spurred in the late 19th century with the opening of the country's first casino, Monte Carlo, and a railway connection to Paris. Since then, Monaco's mild climate, scenery, and gambling facilities have contributed to the principality's status as a tourist destination and recreation center for the rich. In more recent years, Monaco has become a major banking center and has sought to diversify its economy into the services sector and small, high-value-added, non-polluting industries. The state has no income tax, low business taxes, and is well known for being a tax haven. It is also the host of the annual street circuit motor race Monaco Grand Prix, one of the original Grands Prix of Formula One. The principality has a club football team; AS Monaco, who have become French champions on multiple occasions.

Monaco is not formally a part of the European Union, but it participates in certain EU policies, including customs and border controls. Through its relationship with France, Monaco uses the euro as its sole currency (prior to this it used the Mon�gasque franc). Monaco joined the Council of Europe in 2004. It is a member of the Organisation Internationale de la Francophonie.