Known for its sprawling, colorful, and odiferous open-air market, Belén's unusual residential district is a seedy and extremely poor but endlessly fascinating shantytown. Houses are constructed above the waters of the Amazon, and when the river is high, transportation is by canoe. Visitors are free to walk about in dry season (or, for much of the year, to take a locally arranged canoe trip) and see the houses -- some on stilts, others floating during the rainy season; for safety's sake, though, go in a group and during the day only. It's an atmospheric and photogenic place, akin to Calcutta -- you'll see scrappy kids tumbling out of clapboard houses and playing with pet monkeys, and a few houses proudly outfitted with cable TV and other modern conveniences. Most residents of the neighborhood are more than approachable for photos, if you ask respectfully. The animated market, which extends over several blocks, is itself a wild place to visit, with all sorts of extraordinary exotic items for sale, including potions used by faith healers, paiche fish, and yummy Amazonian fruits. Look for the stands set up with blenders, cranking out fruit juices and smoothies (refrigerios and jugos).