Officially the Vatican City State is the Holy See’s independent city state, an enclave within Rome, Italy.
The Vatican City State became independent from Italy with the Lateran Treaty of (1929), and it is a distinct territory under “full ownership, exclusive dominion, and sovereign authority and jurisdiction” of the Holy See, itself a sovereign entity of international law, which maintains the city state’s temporal, diplomatic, and spiritual independence.
With an area of 49 hectares (121 acres) and a population of about 825, it is the smallest state in the world by both area and population.
I visited in 2003 during my trip to Rome and visited the splendid St Peter’s Cathedral but saving the Sistine Chapel for next time (one day!).