There are three countries entirely surrounded by another single country
Three countries are completely enclosed by a single other country: Vatican City (surrounded by Italy), San Marino (surrounded by Italy), and Lesotho (surrounded by South Africa). Additionally, Monaco is almost entirely surrounded by France (with a small coastline), and the Republic of Artsakh (disputed) is similarly enclosed. Vatican City and San Marino are also city-states — Vatican City is the smallest country on Earth at 0.44 km², with a population of about 800. San Marino claims to be the world's oldest republic, founded 301 CE.
Countries with strict borders feel like fundamental geographical facts. The idea that a sovereign nation can exist entirely within another country — a country inside a country — seems paradoxical until you map it. Vatican City is smaller than many shopping centres.
“Three countries are completely surrounded by a single other country: Vatican City and San Marino (both inside Italy) and Lesotho (inside South Africa). Vatican City is smaller than many shopping centres. 🗺️ #OddlyHuman”