Vatican City, Monaco, Nauru, Tuvalu, San Marino and Liechtenstein are in this order the six smallest countries in the world.
Vatican City, a sovereign city-state surrounded by Rome, is about .02 square miles in size and has a population of about 800 people. It is governed by an non-hereditary elected monarchy - the Bishop of Rome otherwise known as the Pope. The Vatican has its own police force that is responsible for public order, traffic control, criminal investigation and border control.
Monaco is .07 square miles is size and lies along the French Riviera on the Mediterranean sea. For its diminutive size, it has an astonishing population of 32,000 people. The Grimaldi family has ruled Monaco since 1297.
Nauru is a tiny Pacific island of 13,000 residents who live on 8.5 square miles. The exact origins of the Nauruans are unclear, since their language does not resemble any other in the Pacific. Phosphate mining has virtually destroyed the tiny nation's ecology, turning its tropical vegetation into a barren, rocky wasteland.
Tuvalu is composed of 9 coral atolls which stretch out for 360 miles in Polynesia. These islands are home to 12,000 inhabitants. Its people make a living mainly through exploitation of the sea, reefs, and atolls and from wages sent home by those abroad (mostly workers in the phosphate industry and sailors)
San Marino, located on Mt. Titano in central Italy is home to 29,000 residents. This country claims to be the oldest country in Europe having been established in 301 AD. San Marino's constitution, dating back to 1600, is the world's oldest written constitution still in effect. More than 50% of the per capita income of the country comes from tourism.
Liechtenstein, home to 34,000 people, is located on the Rhine River between Switzerland and Austria in the alps. Its land mass covers 62 square miles. While it is the smallest German speaking country in the world, it is known for its winter sports and as a tax haven. Liechtenstein is one of the few countries with fewer citizens than registered companies. Its government is a constitutional monarchy ruled by the reigning prince of the Princely House of Liechtenstein. The Prince of Liechtenstein is one of the few monarchs in the world to live in a castle. Parts of this building date from the 12th century although it was rebuilt at the beginning of the 16th century.