ARA Rivadavia (Spanish: [riβaˈðaβja]) was an Argentine battleship built during the South American dreadnought race. Named after the first Argentine president, Bernardino Rivadavia, it was the lead ship of its class. Moreno was Rivadavia's only sister ship.

In 1907, the Brazilian government placed an order for two of the powerful new "dreadnought" warships as part of a larger naval construction program. Argentina quickly responded, as the Brazilian ships outclassed anything in the Argentine fleet. After an extended bidding process, contracts to design and build Rivadavia and Moreno were given to the American Fore River Shipbuilding Company. During their construction, there were rumors that the ships might be sold to a country engaged in the First World War, but both were commissioned into the Argentine Navy. Rivadavia underwent extensive refits in the United States in 1924 and 1925. The ship saw no active service during the Second World War, and its last cruise was made in 1946. Stricken from the naval register in 1957, Rivadavia was sold later that year and broken up for scrap starting in 1959.

Rivadavia's genesis can be traced to the naval arms races between Chile and Argentina which were spawned by territorial disputes over their mutual borders in Patagonia and Puna de Atacama, along with control of the Beagle Channel. These arms races flared up in the 1890s and again in 1902; the latter was eventually stopped through British mediation. Provisions in the dispute-ending treaty imposed restrictions on both countries' navies. The United Kingdom's Royal Navy bought the two Constitución-class pre-dreadnought battleships that were being built for Chile, and Argentina sold its two Rivadavia-class armored cruisers under construction in Italy to Japan.

After HMS Dreadnought was commissioned by the United Kingdom, Brazil decided in early 1907 to halt the construction of three obsolescent pre-dreadnoughts and begin work on two dreadnoughts (the Minas Geraes class). These ships, which were designed to carry the heaviest battleship armament in the world at the time, came as a shock to the navies of South America, and Argentina and Chile quickly canceled the 1902 armament-limiting pact. Argentina in particular was alarmed at the possible power of the ships. The Minister of Foreign Affairs, Manuel Augusto Montes de Oca, remarked that even one Minas Geraes-class ship could destroy the entire Argentine and Chilean fleets. While this may have been hyperbole, either one was much more powerful than any single vessel in the Argentinian fleet. Debates raged in Argentina over whether to spend more than two million pounds sterling to acquire dreadnoughts. With further border disputes, particularly with Brazil near the Río de la Plata (River Plate), Argentina made plans to contract for their own dreadnoughts. After an extended bidding process, Rivadavia and Moreno were ordered from the Fore River Shipbuilding Company in the United States.

Laid down on 25 May 1910, Rivadavia was launched and christened on 26 August 1911 by Isabel, the wife of the Argentine Minister to the United States Rómulo Sebastián Naón. Thousands of people were present to witness the event, including representatives from the Argentine Navy and the country's legation in Washington. The United States sent the assistant chief of the Latin American Division in the State Department, Henry L. James, to be its official representative. Two United States Navy bureau chiefs also attended.

It was reported in January 1913 that apart from the usual fitting-out requirements for Rivadavia and her sister ship ARA Moreno, two Victrola phonographs apiece were included as part of the official specifications.

In mid-September 1913, Rivadavia conducted trials off Rockland, Maine, after a two-week delay due to turbine malfunctions. During speed trials on the 16th, the dreadnought was able to obtain a maximum speed of 22.567 knots (25.970 mph; 41.794 km/h). On a 30-hour endurance trial starting the next day, Rivadavia damaged one of its turbines and had to put in at President Roads, one of Boston Harbor's deep-water anchorages. The turbines were still a problem as late as August 1914. One was dropped by a crane in July and had to be removed for repairs in August.

Over the course of their construction, Rivadavia and Moreno had been the subject of rumors that Argentina would accept the ships and then sell them to Japan, a fast-growing military rival to the United States, or to a European country. The rumors were partially true; some in the government were looking to get rid of the battleships and devote the proceeds to opening more schools, and The New York Times reported in late 1913 that the country had received several offers from interested parties. This angered the American government, which did not want its warship technology offered to the highest bidder. Neither did they want to exercise a contract-specified option that gave the United States first choice if the Argentines decided to sell, as naval technology had already progressed past the Rivadavia class, particularly in the adoption of the "all-or-nothing" armor scheme. Instead, the United States and its State Department and Navy Department put diplomatic pressure on the Argentine government.