Ciudad del Este is Paraguay's second city and the strangest place in the country — a chaotic frontier boomtown on the Paraná river, 327 km east of Asunción, where Paraguay, Brazil and Argentina meet at the Triple Frontier. It was founded in 1957 to anchor the Paraguayan side of the border, and ballooned in the 1980s and 1990s into one of South America's biggest contraband bazaars. Electronics, knock-off perfume, counterfeit watches and bootleg DVDs pour across the Friendship Bridge from Brazil every day; on a busy Saturday you can barely move on Avenida San Blas.
It is, to be blunt, not a pretty city. It is crowded, hot, polluted, famously unsafe after dark, and most travellers use it only as a hinge between Iguazu Falls (on the Argentine and Brazilian sides) and the Itaipú Dam, the second-largest hydroelectric dam in the world, which straddles the Paraná a few kilometres north of town. Both are genuinely world-class sights and easy half-day trips. If you come here, come for them, keep your valuables hidden, and don't linger downtown after sundown.
What the city does have — beyond sheer commercial spectacle — is a surprisingly cosmopolitan character. The Arab community, many of Lebanese descent, is economically dominant and architecturally visible: the Mezquita del Este is the largest mosque in Paraguay. The Friendship Bridge itself is worth walking across once, just to experience the procession of Brazilian shoppers hauling goods in both directions.