Leiden Observatory (Sterrewacht Leiden in Dutch) is an astronomical observatory in the city of Leiden, Netherlands. It was established by Leiden University in 1633, to house the quadrant of Snellius, and is the oldest operating University observatory in the world (before this, astronomy taught at medieval universities tended to be of a more theoretical nature, and any observations were usually done with private equipment rather than at University observatories —see this timeline).
The original observatory used observing platforms on the roof of the main university building at the Rapenburg. In 1860 a large, modern observatory was erected at the Witte Singel. This building was the home of the astronomy department until it moved to the science campus north-west of the city centre in 1974. Although professional astronomical observations are no longer carried out from Leiden itself, the department still calls itself Leiden Observatory. Today's astronomers instead travel to the big observatories, e.g. ESO's VLT in Chile.
The astronomy department (Sterrewacht Leiden) is the largest in the Netherlands and is internationally renowned, performing research in a wide range of astronomical disciplines.
A number of prominent astronomers and physicists have done work at Leiden Observatory, including Willem de Sitter, Ejnar Hertzsprung, and Jan Oort, all of whom have served as Directors. Another famous employee was Jacobus Kapteyn.