The sovereignty of which city was established by 1929's Lateran Treaty?

Vatican City, officially the Vatican City State, is an independent city state and enclave located within Rome, Italy. The Vatican City State, also known simply as the Vatican, became independent from Italy with the Lateran Treaty (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.

The Lateran Treaty was one component of the Lateran Pacts of 1929, agreements between the Kingdom of Italy under King Victor Emanuel III and the Holy See under Pope Pius XI to settle the long-standing Roman Question. The treaty and associated pacts were named after the Lateran Palace where they were signed on 11 February 1929, and the Italian parliament ratified them on 7 June 1929.