text: Post-reunification Mannheim celebrated its 400th anniversary with a series of cultural and other events throughout 2007. The 400th anniversary proper was in 2006, since Frederick IV, Elector Palatine laid the foundations of Mannheim citadel on 17 March 1606. In preparation for the anniversary, some urban activities were implemented, beginning in 2000: the building of the SAP Arena with access to the city's new eastern ring road, the rehabilitation of the pedestrian zone in Breite Straße, the arsenal and the palace, the complete transformation of the old fairground, and the new Schafweide tram line. The concept of the anniversary of the city is aimed at a diverse range of events without a dominant central event. In 2001, the City hospital was officially and legally awarded with the title University Hospital Mannheim. In 2023, Mannheim hosted the Bundesgartenschau 2023 (National Garden Show); the second time after 1975.
  Geography
  Climate
  Mannheim is located in Germany's warmest summer region, the "Rhine shift". In summer, temperatures sometimes rise up to  and higher. The highest recorded temperature was  on 7 August 2015. The daily lows during heat waves can be very high for the latitude (around ). In September 2016, the average temperature in Mannheim was 18.6 °C, highest in Baden-Württemberg.
  In comparison to other regions of Germany, Mannheim has a higher humidity in summer which causes a higher heat index. Snow is rare, even in the cold months. Precipitation occurs mostly during afternoon thunderstorms during the warmer period (average days of thunderstorms in a year is 40–50). The climate in this area has mild differences between highs and lows, and there is adequate rainfall year-round. The Köppen Climate Classification subtype for this climate is "Cfb" (Marine West Coast Climate/Oceanic climate), bordering closely on a humid subtropical climate (Cfa), with summer months often averaging above 21 degrees (71 F).
  Demographics