Buenos Aires’s largest barrio, Palermo enjoys the city’s widest open spaces—thanks to 19th-century dictator Juan Manuel de Rosas, whose private estate stretched from Recoleta to Belgrano, between present-day Avenida del Libertador and the Río de la Plata. After his defeat at the battle of Caseros in 1852, Rosas went into exile in Great Britain, and his properties became Parque Tres de Febrero.

Once part of the capital’s unsavory arrabales (margins), its street corners populated by stylish but capricious malevos (bullies) immortalized in Borges’s short stories, Palermo hasn’t entirely superseded that reputation—some poorly lighted streets still make visitors uneasy. Yet it also has exclusive neighborhoods such as Barrio Parque, the embassy row also known as PalermoChico, immediately north of Recoleta.

Across Avenida del Libertador, the Botánico is an upper-middle-class neighborhood that takes its name from the Jardín Botánico Carlos Thays (Avenida Santa Fe 3951, tel. 011/4831-4527, 8 a.m.–6 p.m. daily, free), an otherwise appealing botanical garden infested with feral cats. Opposite nearby Plaza Italia, the Jardín Zoológico (Avenida Las Heras s/n, tel. 011/4806-7412, www.zoobuenosaires.com.ar, 10 a.m.–6 p.m. Tues.–Sun.) is an ideal outing for visitors with children (free up to age 12). General admission costs US$3 per adult.

The real center of action, though, is across Avenida Santa Fe at PalermoViejo, where Plaza Serrano (also known as Plaza Cortázar) is a major locus of local nightlife. PalermoViejo subdivides into PalermoSoho, a trendy term to describe the area south of Avenida Juan B. Justo, and the more northerly PalermoHollywood, where many television and radio producers have located their facilities. Shaded by sycamores, many PalermoViejo streets still contain casas chorizo (sausage houses) on deep, narrow lots. One of the most interesting private residences is the Casa Jorge García (Gorriti 5142), whose garage facade features Martiniano Arce’s filete caricatures of the García family.

Palermo’s most conspicuous new landmark is the controversial Centro Cultural Islámico Rey Fahd (Avenida Bullrich 55, tel. 011/4899-1144, www.ccislamicoreyfahd.org.ar), built with Saudi money on land acquired from the Menem administration. It’s open for guided tours only Tuesday and Thursday noon–1 p.m. To the north, overlapping Belgrano, Las Cañitas is a gastronomic and nightlife zone challenging PalermoViejo among porteño partygoers.