Part of the Tijuca National Park, this is one of the world's largest urban forests. By the mid-19th century, Tijuca Forest was practically deforested, first for lumber, then for coffee plantations. In 1861, the government recognized that deforestation was hurting local rainfall, leading to a shortage of potable water. The forest is now one of the city's most important protected areas. If you're lucky, you'll see monkeys and a variety of butterflies. Beautiful spots include the Cascatinha (a lovely waterfall), the Mayrink Chapel, the Lago da Fada (Fairy Lake), the Acude da Solidao (Solitude Dam) and several caves. We recommend you take a Jeep tour, which can be arranged through most hotels. If you're determined to go on foot without a guide, the best place to start is Cascatinha, which is close to the main park entrance. Just remember that many people get lost in the forest, so stay on the marked trails at all times. Daily 8 am-7 pm. Admission is free. The main entrance is at Praca Alfonso Vizeu, Alto da Boa Vista, Rio de Janeiro. Phone 21-2492-2253. http://www.amigosdoparque.org.br.