People walk at Estrada das Paineiras ( Paineiras Road ) in The Tijuca Forest ( Floresta da Tijuca in Portuguese ), a mountainous hand-planted rainforest in the city of Rio de Janeiro, Brazil - it is an UNESCO World Heritage Site and the world's largest urban forest, covering some 32 km² (12.4 mi²) - The Tijuca Forest is home to hundreds of species of plants and wildlife, many threatened by extinction, and found only in the Atlantic Rainforest (Mata Atlantica in Portuguese). The vegetation is so dense that scientists have estimated that ambient temperatures in surrounding areas have been lowered by up to 9 °C.