Lesotho is the largest country completely surrounded by another country. The mountainous kingdom, covering about 30,355 square kilometres, is entirely enclosed by South Africa.
This geographic arrangement makes Lesotho an enclave as well as a landlocked country. Its border with South Africa runs for roughly 909 kilometres, and every route to another country passes through South African territory. Lesotho is also unusual because its entire territory lies above 1,000 metres in elevation; its lowest point is about 1,400 metres above sea level.
Lesotho became a British protectorate in 1868 and gained independence on 4 October 1966. It is one of only three sovereign states completely surrounded by another sovereign state. The other two are Vatican City and San Marino, both enclosed by Italy, but they are tiny microstates. That distinction is why Lesotho is the largest answer rather than one of the European enclaves.