Vatican City holds the title of the smallest independent state in the world, both by area and population. It is an enclave entirely surrounded by the city of Rome, Italy. Spanning only about 44 hectares (109 acres), it is a sacerdotal-monarchical state ruled by the Pope. Established in 1929 via the Lateran Treaty, it functions as a distinct entity from the Holy See. Despite its tiny size, it operates its own postal system, radio station, and banking system. It also maintains its own small military force, the Swiss Guard, which has protected the Pope since 1506. The entire state is designated as a UNESCO World Heritage site, housing priceless art and architecture including St. Peter's Basilica and the Sistine Chapel. Its permanent population is less than 1,000 people, most of whom are clergy or members of the Swiss Guard. Citizenship is not based on birth but is granted 'jus officii' (by virtue of office) to those who work there.