The Atacama Large Millimeter Array (ALMA) is an Interferometer array of Radio Telescopes on the Chajnantor plateau in the Atacama Desert in Chile. Construction began in November 2003 and inauguration was on March 13, 2013. It sits at an altitude of 5000 meters and consists of 66 12-meter and 7-meter movable dishes that observe millimeter and sub-millimeter Wavelengths.

Operation began with 50 12-meter dishes. A later additional called the Atacama Compact Array (ACA) consists of sixteen additional 12-meter and 7-meter dishes with different characteristics, including a wider Field of View.