Heidelberg Hauptbahnhof (commonly known as Heidelberg Hbf) is the main railway station for the city of Heidelberg. In 2005 it was used by around 42,000 passengers per day and is one of the largest passenger stations in the German state of Baden-Württemberg. The station is classified by Deutsche Bahn as a category 2 station.

The first station was built in 1840 as a terminus near Heidelberg's old town, Altstadt, at the site of the modern Adenauerplatz. Urban problems as a result of the extension of part of the station to form a through station in 1862 and a lack of expansion options resulted in a decision the early 20th century to relocate the station as a new through station a kilometre to the west. Interrupted by two world wars, the relocation of the Heidelberg railway facilities took over 50 years. Inaugurated in 1955, the station is now considered to be "the most beautiful and architecturally interesting buildings of Deutsche Bundesbahn", and since 1972 it has been listed as a "cultural monument of special importance" under the historical monuments register of Baden-Württemberg. The station is located in Willy-Brandt-Platz about two kilometres west of central Heidelberg. Diagonally opposite is the former headquarters of Heidelberger Druckmaschinen. It is served by the Rhine-Neckar S-Bahn.

On 12 September 1840 the original terminal station was opened in Heidelberg at the end of the first section of the Baden Mainline from Mannheim Hauptbahnhof. It was decided to build the station as a terminal station so that it could be as close as possible to the city. The station was between today's Poststraße and Bahnhofstraße and the station forecourt fronted the Rohrbacherstraße. The station, which was designed by the architect Friedrich Eisenlohr, consisted of several simply designed buildings in a neoclassical style with romantic and ornamental elements. The main building was built on the side towards the city from red Neckar sandstone and it was covered with a contrasting slate roof. The two-span wooden train shed covered four platform tracks and it was comparatively large for the period at 75 metres long and 28 metres wide. The exit of the station platform was flanked by two gate towers, used as water towers. Within the station there were six sets of points and 15 turntables on which light carriages could be rotated manually. According to the first timetable, four trains ran daily to Mannheim, requiring a running time of 35 to 40 minutes.

In 1843, the line was opened from Heidelberg to Karlsruhe Hauptbahnhof. In 1846, the Main-Neckar Railway opened to Frankfurt and a second station was completed in 1848 with "architecture in an exemplary manner" and was integrated into the existing station track field. The station was also designed by Eisenlohr and was largely symmetrical to the existing station infrastructure, the construction of which had made allowance for a possible extension to the north. Because the Main-Neckar Railway was a standard gauge line, in contrast to 1600 mm broad gauge of the Baden State Railway until it was regauged in April 1855, all freight had to be transhipped, using a freight shed in the middle of the station. The two main station buildings were linked by an arcade in the centre of which was a gateway that served as the main entrance to the station. In addition, there were two mixed gauge tracks connecting to a roundhouse and via a transfer table to a carriage shed. The station remained in this basic form for the next 100 years.

With the opening of the Odenwald Railway in 1862, the station became a through station and was extended slightly to the south. In 1873 Heidelberg became the terminus of a branch line to Schwetzingen and Speyer. In 1864, a connecting curve was opened between the lines to Mannheim and Karlsruhe in order to relieve the station. A new freight yard and marshalling yard were built in 1873 west of Römerstraße along the route to Mannheim.

At the beginning of the 20th century the development of Bergheim to the north of the station and modern Weststadt to the south of it prevented the extension of railway precinct. In 1902, 340 trains operated on weekdays from Heidelberg station. In the timetable of 1954/1955 over 400 services ran. Important long-distance trains bypassed Heidelberg, because the capacity of the station was exhausted.

At the same time the station was affected by town planning. With increased road traffic following the construction of the Odenwald Railway in 1862, the level crossing of Rohrbacher Straße in the modern Adenauerplatz, in particular, proved to be annoying. At the end of 1949, 10,800 vehicles passed through the crossing, which was closed to road traffic for three to four hours each day. A pedestrian underpass was opened there in 1893. Passengers on the Heidelberg tramway had to pass through the crossing on foot as the tram lines ended on both sides of the level crossing.

In 1873, there was consideration of relocating the railway station. This was opposed by hoteliers whose businesses were located in the area. When one of the wooden station buildings burnt down in 1892, some spectators wished that the flames had spread to the whole station. The nationalisation of the Main-Neckar Railway in 1895 facilitated the development of initial plans in the 1890s. First, the city's preference was that the station be raised in its old central location. In 1901, the Heidelberg citizens' committee approved a proposal of the Baden State Railways to build a new through station a good kilometre west of the old site. It envisaged the construction of 20 platform tracks. The total construction costs was estimated to be 40 million marks.