The National Astronomical Observatory of Chile (OAN) can be traced back to the Gillis Expedition, a project of the United States Naval Observatory, led by James Melville Gilliss, who arrived in Chile in 1849 to observe Mars and Venus from the southern hemisphere so as to improve solar parallax.

[2][3] Gilliss and his party set up their equipment on Santa Lucia Hill, a small rise in downtown Santiago.

[4] After completing the project in 1852, Gilliss sold the equipment and the buildings which housed it to the Government of Chile, which formed OAN at that time.

Rutllant played an important part in bringing foreigners in to build the big observatories in the Atacama Desert in the 1960s.

[10] Beginning in 1962, the Soviet Union also sent astronomers and provided several telescopes to OAN , but it withdrew after the 1973 Chilean coup d'état.

It was built by the University of Chile in 1967 to house a 70 cm (28 in) Maksutov telescope provided by the Soviet Union, which began operating in 1968.