Heidelberg (; Palatine German: Heidlberg) is a city in the German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914, of which roughly a quarter consisted of students. Located about south of Frankfurt, Heidelberg is the fifth-largest city in Baden-Württemberg. Heidelberg is part of the densely populated Rhine-Neckar Metropolitan Region. Heidelberg University, founded in 1386, is Germany's oldest and one of Europe's most reputable universities. Heidelberg is a scientific hub in Germany and home to several internationally renowned research facilities adjacent to its university, including the European Molecular Biology Laboratory and four Max Planck Institutes. The city has also been a hub for the arts, especially literature, throughout the centuries, and it was designated a "City of Literature" by the UNESCO Creative Cities Network. Heidelberg was a seat of government of the former Electorate of the Palatinate and is a popular tourist destination due to its romantic cityscape, including Heidelberg Castle, the Philosophers' Walk, and the Baroque old town. Geography Heidelberg is located on the eastern edge of the Upper Rhine Plain (German: "Oberrheinebene"), at the place where the river Neckar leaves its narrow valley through the Odenwald mountains and begins the last leg of its journey across the plain towards Mannheim, where it merges into the Rhine about 20 kilometers downstream. A part of Heidelberg, including the historical old town and the famous Heidelberg Castle, is located in the narrow Neckar valley. Other parts (mostly quarters from around the 19th century or newer, or originally independent, later incorporated villages) sprawl out into the Rhine Plain and along the Bergstraße (route) ("mountain road"), the narrow strip of characteristic landscape along the sharp border between the plain and the Odenwald mountains. The town is bordered by the Königstuhl (568 m), the Gaisberg (375 m) and the Heiligenberg (445 m) mountains. Heidelberg is on European walking route E1 (Sweden-Umbria). Flora and fauna Heidelberg is among the warmest regions of Germany and plants atypical of the central-European climate flourish there, including almond and fig trees, many kinds of palm trees and olive trees. Alongside the Philosophenweg (Philosophers' Walk) on the opposite side of the Old Town, winegrowing was restarted in 2000. There is a wild population of African rose-ringed parakeets, and a wild population of Siberian swan geese, which can be seen mainly on the islands in the Neckar near the district