Amazon Tall Tower Observatory, Research tower in São Sebastião do Uatumã, Brazil.

The Amazon Tall Tower Observatory is a research tower that rises above the rainforest canopy and is equipped with scientific instruments that collect data continuously. The structure allows scientists to study forest-atmosphere interactions across a large region.

The project was launched in 2009 as a German-Brazilian collaboration coordinated by the Max Planck Institute for Biogeochemistry and Brazil's National Institute of Amazonian Research (INPA). The two 80-metre towers were operational by 2012; construction of the 325-metre tower began on 15 September 2014 and it was inaugurated on 22 September 2015.

The site lies about 150 km southwest of Manaus, far from any settlement, so staff live at a base camp with climate-controlled containers holding laboratory equipment and an office. In the wet season the prevailing winds bring air resembling the pre-industrial atmosphere; in the dry season pollution from Manaus and the deforestation arc reaches the towers.

The tower is accessible only to authorized researchers and technical staff who work with specialized equipment. Visitors should note that this is a research facility, not a tourist attraction.

The 325-metre tower is one metre taller than the Eiffel Tower and is the tallest structure in South America. Its counterpart, ZOTTO, stands in the Siberian taiga of Russia. In the wet season, winds bring air to the site that resembles the pre-industrial atmosphere; in the dry season, pollution from Manaus and the arc of deforestation reaches even here.