Vatican City is the world’s only sovereign state whose territory consists entirely of one city.
Vatican City is an independent city-state enclosed within Rome, Italy. It was established by the Lateran Treaty of 1929, which settled the relationship between the Holy See and the Kingdom of Italy and created the modern territorial state.
With an area of about 49 hectares, or 0.49 square kilometres, Vatican City is the smallest internationally recognised independent state by both area and population. It is the spiritual and administrative centre of the Catholic Church and the residence of the pope.
The Holy See and Vatican City are related but not identical. The Holy See is the central governing authority of the Catholic Church and maintains diplomatic relations; Vatican City is the territory that supports its independence. Monaco, Singapore and San Marino are also small sovereign states, but their territories are not simply one city in the same constitutional sense.