The Vatican City became independent from Italy in 1929 under the Lateran Treaty and it remains the world's smallest state at just 0.49 square kilometers or 0.19 square miles, according to Visual Capitalist. Falling under the "full ownership, exclusive dominion, and sovereign authority and jurisdiction" of the Holy See, the Vatican City has enormous influence for its size given that there are more than 1.2 billion Catholics all over the world.
The Mediterranean enclave of Monaco is the second-smallest country worldwide at just over two square kilometers or 0.78 square miles. It is well known for entirely different reasons, especially given its reputation as a playground for the rich and its iconic grand prix. With 19,009 inhabitants per square kilometer, Monaco is the most densely populated sovereign state in the world.