The Vienna Observatory (German: Universitätssternwarte Wien) is an astronomical observatory in Vienna, Austria. It is part of the University of Vienna. The first observatory was built in 1753–1754 on the roof of one of the university buildings.

A new observatory was built between 1874 and 1879, and was finally inaugurated by Emperor Franz Joseph I of Austria in 1883. The main dome houses a refractor with a diameter of 68 centimetres (27 in) and a focal length of 10.5 metres (34 ft) built by the Grubb Telescope Company. At that time, it was the world's largest refracting telescope.

Land for the new observatory was purchased in 1872, and was noted for having increased elevations (about 150 ft) above the city. Construction started in March 1874, and it was opened with new instruments in 1877. The overall design had various rooms and three main domes, one for the Grubb refractor and then two smaller domes, and some terraces.

At this time there were larger aperture reflecting telescopes, and the main technologies of metal mirror and silver on glass; however they had not yet established a strong reputation for themselves and there continued a strong interest in refractors for better or worse until the 20th century.

A report published in the publication Nature in notes that the 69 cm / 27-inch Grubb observed planets, comets, and nebula between 1903 and 1906. Observations with a 6-inch Fraunhofer refractor telescope of comets and planets between 1903 and 1910 was also noted.

• List of largest optical refracting telescopes
• Kuffner Observatory (Established in the 1886, also in Vienna)
• List of Jesuit sites

• University of Vienna Institute of Astronomy home page
• Early Asteroid Research in Austria