Commonly describing the area surrounding Plaza San Martín but taking in everything north of Avenida Córdoba and parts of Barrio Norte, Retiro was home to an isolated 17th-century monastery and then a slave market, bullring, and cavalry barracks. After independence, it became a zone of quintas (country houses); by 1862, General San Martín’s equestrian statue marked its definitive urbanization, and on the centenary of his birth in 1878, mayor Torcuato de Alvear turned the plaza into a public park. From the late 19th century, the surrounding streets became the city’s elite residential area.

The most extravagant residence, dating from 1909, was the Palacio Paz (Avenida Santa Fe 750, tel. 011/4311-1071, ext. 147, www.palaciopaz.com.ar), a 12,000-square-meter Francophile mansion built for La Prensa newspaper founder José C. Paz. It now houses the Círculo Militar (www.circulomilitar.org) and is open for guided tours (US$5 pp) in Spanish at 11 a.m. and 3 p.m. Tuesday–Friday and 11 a.m. Saturday; English-speaking tours (US$9 pp) take place at 3:30 p.m. Wednesday–Thursday. Another part of the building serves as the army’s Museo de Armas (Weapons Museum, Avenida Santa Fe 702, tel. 011/4311-1071, ext. 179, 3–7 p.m. weekdays only, US$0.80).

On the plaza’s north side, dating from 1905, the art nouveau Palacio San Martín (Arenales 761, tel. 011/4819-8092, free) was originally a three-house complex built for the Anchorena family. When not needed for protocol and ceremonial purposes, it’s open for guided tours at 2:30 p.m. Tuesday–Wednesday.

At the plaza’s southeast edge, dating from 1935, the 33-story Edificio Kavanagh (Florida 1035) was Buenos Aires’s first skyscraper—and its first air-conditioned building. At the northeast corner, the Monumento a los Caídos de Malvinas is a marble monument with names of those who died in the 1982 Falkland Islands War with Britain. Across Avenida del Libertador, the Plaza Fuerza Aérea Argentina, once known as Plaza Britania, was renamed after the war, when Argentina’s air force was the only branch of the military that performed credibly; its centerpiece, though, is still architect Ambrose Poynter’s Torre de los Ingleses (1916), a Big Ben clone donated by the Anglo-Argentine community.

South of Plaza San Martín, literary great Jorge Luis Borges resided in an apartment at Maipú 994, immediately south of the weapons museum. The beaux arts Centro Naval (Naval Center, Florida 801, www.centronaval.org.ar) dates from 1914.

Across Avenida 9 de Julio, facing Plaza Lavalle, the Plateresque Teatro Nacional Cervantes (1921) is one of the capital’s key theater venues. At the barrio’s southwestern edge, a block north of the Cervantes, the Museo de la Shoá (Montevideo 919, tel. 011/4811-3537, www.fmh.org.ar, 11 a.m.–7 p.m. Mon.–Thurs., 11 a.m.–4:30 p.m. Fri., US$1.30) is a small but professional Holocaust museum with an Argentine focus.