Recognized internationally for its quality of work in the field of positional astronomy (since the 19th century), in 1992, it became a dependency of the University of Lisbon (and later, part of the Faculty of Sciences), responsible for scientific and historical research, along with media relations.

It was established in the mid-19th century with the aim of promoting new Sidereal Astronomy, discovery and understanding of the infinite cosmos, and concern about the exact mapping of the sky and measuring the size of the universe.

[1] In 1850, Hervé Faye and Friedrich Georg Wilhelm von Struve (1793-1864) proposed that astronomical observations should be taken in Lisbon, being the first and "unique locale in all of continental Europe that the zenithal telescope could encounter the marvelous Argelander star".

The commission thought, initially, of constructing the new building in the Prince Royal's garden, then alternately in the Parque Eduardo VII and later the Tapada da Ajuda.

[1] Wilhelm Struve, then-director at Pulkova offered his services to the Portuguese government and became the main adviser, playing a very important role in the choice of equipment and the orientation of astronomer Frederico Augusto Oom (1830-1890), who was given a rough 5-year training session.

Oom, was as a Navy Lieutenant and hydrographic engineer, who eventually became the first director of the Royal Astronomical Observatory of Lisbon and who ultimately had a very important role in the whole foundation of this building.

[1] Between 1900 and 1901, the observatory participated in the solar parallax campaign, centered on the observations of the asteroid Eros, using a circular meridian measuring instrument to improve the value of the Astronomical unit.