Leiden ( LY-dən; Dutch: [ˈlɛidə(n)] ; in English and archaic Dutch also Leyden) is a city and municipality in the province of South Holland, Netherlands. The municipality of Leiden has a population of 127,046 (31 January 2023), but the city forms one densely connected agglomeration with its suburbs Oegstgeest, Leiderdorp, Voorschoten and Zoeterwoude with 215,602 inhabitants. The Netherlands Central Bureau of Statistics (CBS) further includes Katwijk in the agglomeration which makes the total population of the Leiden urban agglomeration 282,207. Further, Teylingen, Noordwijk, and Noordwijkerhout are included in the larger Leiden urban area, which has 365,913 inhabitants. Leiden is located on the Oude Rijn, at a distance of some 20 km (12 mi) from The Hague to its south and some 40 km (25 mi) from Amsterdam to its north. The recreational area of the Kaag Lakes (Kagerplassen) lies just to the northeast of Leiden.
A university city since 1575, Leiden has been one of Europe's most prominent scientific centres for more than four centuries. University buildings are scattered throughout the city and the many students from all over the world give the city a bustling, vivid and international atmosphere. Many important scientific discoveries have been made here, giving rise to Leiden's motto: 'City of Discoveries'. The city houses Leiden University, the oldest university of the Netherlands, and Leiden University Medical Center. Leiden University is one of Europe's top universities, with thirteen Nobel Prize winners. It is a member of the League of European Research Universities and positioned highly in all international academic rankings. It is twinned with Oxford, the location of the United Kingdom's oldest university. Leiden University and Leiden University of Applied Sciences (Leidse Hogeschool) together have around 35,000 students. Modern scientific medical research and teaching started in the early 18th century in Leiden with Boerhaave.
