Heidelberg (; ; ) is the fifth-largest city in the German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of students, it is Germany's 51st-largest city. Located about south of Frankfurt, Heidelberg is part of the densely populated Rhine-Neckar Metropolitan Region which has its centre in Mannheim.

Heidelberg is located on the Neckar River, at the point where it leaves its narrow valley between the Oden Forest and the Little Oden Forest, and enters the wide Upper Rhine Plain. The old town lies in the valley, the end of which is flanked by the Königstuhl in the south and the Heiligenberg in the north. The majority of the population lives in the districts west of the mountains in the Upper Rhine Plain, into which the city has expanded over time.

Heidelberg University, founded in 1386, is Germany's oldest and one of Europe's most reputable universities.Its latest overall ranking positions range from 5th to 18th in Europe; the peer review scores, reflecting academic esteem, are usually higher. It was never ranked outside Europe's top 20 by any major university ranking. See rankings. 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 (), 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 (), 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, and many kinds of palm trees and olive trees. Alongside the on the opposite side of the Old Town, winegrowing was restarted in 2000.

There is a wild population of African rose-ringed parakeets,Stefanie Wegener: Verbreitung und Arealnutzung der Halsbandsittiche (Psittacula krameri) in Heidelberg, published by: Ornithologische Gesellschaft Baden-Württemberg e. V., Ornithol. Jh. Bad.-Württ. 23: 39–55 (2007) and a wild population of Siberian swan geese, which can be seen mainly on the islands in the Neckar near the district of Bergheim.

Administrative structures

Heidelberg is a unitary authority within the Regierungsbezirk Karlsruhe. The Rhein-Neckar-Kreis rural district surrounds it and has its seat in the town, although the town is not a part of the district. Heidelberg is a part of the Rhine-Neckar Metropolitan Region, often referred to as the Rhein-Neckar Triangle.

This region consists of the southern part of the State of Hessen, the southern part of the State of Rhineland-Palatinate (), the administrative districts of Mannheim and Heidelberg, and the municipalities of the Rhein-Neckar-Kreis. The Rhein-Neckar Triangle became a European metropolitan area in 2005.

Heidelberg consists of 15 districts distributed in six sectors of the town. In the central area are Altstadt (the Old Town), Bergheim and Weststadt; in the north, Neuenheim and Handschuhsheim; in the east, Ziegelhausen and Schlierbach; in the south, Südstadt, Rohrbach, Emmertsgrund, and Boxberg; in the southwest, Kirchheim; in the west, Pfaffengrund, Wieblingen, and a new district, named , is built on land in Weststadt and Wieblingen. The new district will have approximately 5,000–6,000 residents and employment for 7,000. Further, new residential space for 10,000–15,000 residents was made available in Patrick Henry Village following the departure of the US Armed Forces.

Neighbouring communes The following towns and communes border the city of Heidelberg, beginning in the west and in a clockwise direction: Edingen-Neckarhausen, Dossenheim, Schriesheim, Wilhelmsfeld, Schönau, Neckargemünd, Bammental, Gaiberg, Leimen, Sandhausen, Oftersheim, Plankstadt, Eppelheim (all part of the Rhein-Neckar-Kreis), and Mannheim.

Climate Heidelberg has an oceanic climate (Köppen climate classification Cfb), defined by the protected valley between the Pfälzerwald and the Odenwald. The almost year round warm temperatures are usually determined by Atlantic air masses in the winter and increased influence from the western Mediterranean in summer. In contrast to the nearby Upper Rhine Plain, Heidelberg's position in the valley leads to more frequent easterly winds than average. The hillsides of the Odenwald favor clouding and precipitation.

Spring starts earlier than the average in Germany (usually mid February in the recent years). While the weather in spring is typically warm, it is also known to change far more often than in the summer.

Summer starts typically in June and stays until September. In this time the weather is typically stable, with single thunderstorms marking the only precipitation. Day temperatures of around 30 °C are typical, but can reach up to 40 °C during heat waves.

Autumn starts warm in September and cools down to typical winter temperatures for the region by the end of November. Precipitation levels begin to increase and, due to the decreasing sunlight, the region is affected by fog more frequently from the second part of October onwards.

Winters are mostly mild, though light nighttime frosts do occur in the coldest months. Snow is a rare event, and precipitation normally falls as rain. Winters are the wettest time of the year, with frequent western winds blowing from the Atlantic. Storms ("Orkane") can create severe damage, and the Neckar is often affected by floods.

According to the German Meteorological Service, Heidelberg was the warmest place in Germany in 2009.Mechthild Henneke: Wetterextreme in Deutschland 2009. In: Südkurier, 28. April 2010Kreisbeschreibung Bd. 1, S. 54ff

History

Early history Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907. Scientific dating determined his remains as the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of worship were built on the , or "Holy Mountain". Both places can still be identified. In 40 AD, a fort was built and occupied by the 24th Roman cohort and the 2nd Cyrenaican cohort (CCG XXIIII and CCH II CYR). The late Roman Emperor Valentinian I, in 369 AD, built new and maintained older castra (permanent camps) and a signal tower on the bank of the Neckar. They built a wooden bridge based on stone pillars across it. The camp protected the first civilian settlements and was eventually captured by Germanic tribes. The local administrative centre in Roman times was the nearby city of Lopodunum, today known as Ladenburg.

Middle Ages

Modern Heidelberg can trace its beginnings to the fifth century. The village is first mentioned for that period in documents dated to 769 AD. now lies in the middle of modern Heidelberg. The people gradually converted to Christianity. In 870 AD, the monastery of St. Michael was founded on the Heiligenberg inside the double rampart of the Celtic fortress. Around 1130, the Neuburg Monastery was founded in the Neckar valley. At the same time, the bishopric of Worms extended its influence into the valley, founding Schönau Abbey in 1142. Modern Heidelberg can trace its roots to this 12th-century monastery. The first reference to Heidelberg can be found in a document in Schönau Abbey dated to 1196. This is considered to be the town's founding date. In 1156, Heidelberg castle and its neighboring settlement were taken over by the house of Hohenstaufen. Conrad of Hohenstaufen became Count Palatine of the Rhine (). In 1195, the Electorate of the Palatinate passed to the House of Welf through marriage. In 1214, Ludwig I, Duke of Bavaria acquired the Palatinate, as a consequence of which the castle came under his control. By 1303, another castle had been constructed for defense. In 1356, the Counts Palatine were granted far-reaching rights in the Golden Bull, in addition to becoming Electors. In 1386, Heidelberg University was founded by Rupert I, Elector Palatine.Heike Hawicks / Ingo Runde: Heidelberg and the Holy See – from the Late Medieval Reform Councils to the Reformation in the Electoral Palatinate, in: 1517. Le università e la Riforma protestante. Studi e ricerche nel quinto anniversario delle tesi luterane (Studi e ricerche sull'università), ed. Simona Negruzzo, Bologna 2018, S. 33–54.

Modern history

Heidelberg University played a leading part in Medieval Scholasticism, Renaissance humanism, the German Reformation, and in the subsequent conflict between Lutheranism and Calvinism during the 15th and 16th centuries. In April 1518, a few months after proclaiming his Ninety-five Theses, Martin Luther was received in Heidelberg, to defend them.

Heidelberg's library, founded in 1421, is the oldest existing public library in Germany.

In 1537, the castle located higher up the mountain was destroyed by a gunpowder explosion. The duke's palace was built at the site of the lower castle.