Embassy of the United States to the Holy See to the Holy See, previously located on Aventine Hill, moved to new headquarters in September 2015 in a separate building on the same compound as the United States Embassy Rome. Embassy of the United States to the Holy See The Embassy of the United States of America to the Holy See (or Embassy Vatican for short) is the diplomatic mission of United States of America to the Holy See, a term referring to the central government and universal reach of the Roman Catholic Church. The current embassy moved to new headquarters in September 2015 in a separate building on the
Foreign relations of the Holy See time. Currently it has the territory of the State of the Vatican City under its direct sovereign rule. In the period of 1870-1929 between the annexation of Rome by the Kingdom of Italy and the ratification of the Lateran Treaty establishing the current Vatican City State, the Holy See was devoid of territory. In this period some states suspended their diplomatic relations, but others retained them (or established such relations for the first time or reestablished them after a break), so that the number of states that did have diplomatic relations with the Holy See almost doubled (from 16 to