The Amazon Tall Tower Observatory or ATTO (in Portuguese: Observatório de Torre Alta da Amazônia) is a scientific research tower in the Amazon rainforest with a height of 325 metres (1,066 ft). The site is distant from any human presence, about 150 kilometres northeast of Manaus. The tower, South America's tallest structure, is used to study the climate in the largely untouched rainforest surrounding it. It measures greenhouse gases, aerosols and weather data and provides information about a roughly 100 square kilometer area around the tower.