Sister cities of San Isidro, Buenos Aires

San Isidro is a municipality in Greater Buenos Aires and one of the most affluent municipalities in Argentina. It is located in San Isidro Partido in the Buenos Aires Province.

The centre of San Isidro is an historic area with cobbled streets and old single-story houses. At its heart is Plaza Mitre, with the neo-gothic San Isidro cathedral of 1898 rising above. The sloping plaza, also home to the recently opened Rugby Museum, hosts an antiques and crafts fair. The plaza leads down to the Río de la Plata, where the riverside park is popular with mate drinkers and tourists. The city is called the "National Capital of Rugby" in Argentina, due to being the cradle of many important players and hosting the national rugby union's derby match between CASI and SIC.

San Isidro is served by two rail lines, the Mitre Line and the Tren de la Costa (Train of the Coast in English), at the San Isidro R station, a vintage 1891 built in the style of British stations, in Its facilities are located a shopping arcade, cinemas, and restaurants. The station is located barely 200 meters from the Cathedral of San Isidro.

Many large houses surround the historic centre and line the riverside. The oldest is the House of General Pueyrredón, built in 1790 by Juan Martín de Pueyrredón and expanded by his son Prilidiano Pueyrredón. The house, with its old giant algarrobo tree under which Pueyrredón and San Martín discussed independence, is a national historic monument and hosts the municipal historic museum of San Isidro. The home of writer Victoria Ocampo, the Villa Ocampo, is owned by Unesco and is also open to the public.

The San Isidro Hippodrome is one of Argentina's most important racecourses and covers a large part of the area inland from the city. Built in striking 1930s architectural style, the racecourse has faced tough times since the economic crises of the late 20th and early 21st centuries.

In 2007 San Isidro celebrated its 300 years of existence with many different celebrations taking place in the hippodrome and other places. The settlement was first incorporated in 1784 as the Alcaldía de la Hermandad, and was granted municipality status by the province in 1850. It maintains sister city relationships with Herzliya, Israel; Nagoya, Japan; and San Isidro, Peru.