The beginnings of Berlin's underground

At first sight, Berlin’s underground seems to be only half as interesting as that of other European capitals. It has no ancient Christian catacombs like Rome or mining tunnels like Paris which date back to the 13th century. The lowland plain of the Berlin-Warsaw glacial valley, which originated during the ice age, largely consisted of swamps and sandy soil. Water could already be found just three metres beneath the surface. Consequently, there was little underground building – with the exception of a few ice cellars, storage depots and burial grounds.

The city’s fortifications, going back to 1650, are no underground buildings as such since they were built at ground level and then covered with soil. The first people to actively build into Berlin's underground were the beer brewers. Since 1860 they built brewery cellars which extended up to 18 metres into the ground. These structures were built on the Teltow and Barnim heights bordering the glacial valley because there were no problems with the water table there. These traditional brewery sites can still be found in the districts Schoeneberg, Kreuzberg, Neukoelln, Prenzlauer Berg and Wedding.

The construction of the water supply system began in 1852 and of the canalization or sewage system in 1873. This was urgently necessary, as the hygienic conditions were abysmal, and untreated sewage was making its way into the rivers and canals. Cholera and Typhus epidemics were the result. In 1876, the first sewage canals were brought on-line and the Berlin pneumatic post system was made open to the public. About five years later work was begun on the telephone network, although this didn’t affect the popularity of the pneumatic post. Finally in 1888 the fist electric street lights could be turned on, and around 1895 most of the city’s supply lines were underground.

After the Franco-Prussian War of 1871 the German Empire was founded. Berlin, the new imperial capital, experienced a never-before seen building boom. The population doubled and tripled, and the city grew far beyond its old borders. Since the cost of land exploded, buildings were built on filled waterways and marshlands. For larger buildings a new “pile foundation” construction method came into use. Next to one another, logs were driven into the ground up to 15 metres deep, until they reached load bearing ground. On top of these, building foundations were laid. For example, the base of the Reichstag dome sits on 2232 such logs that were rammed into the ground with steam powered pile drivers to stabilize the building foundation.

Attempts were also made to relieve the clogged streets by going underground. The electrical companies AEG and Siemens competed to build an underground transportation network. AEG wished to build a deep tunnel system using the London Tube as a model, and built two test tunnels, known as the AEG-Tunnel and the Stralauer Spreetunnel, which were innovative masterpieces for their time. In the end though, Siemens was given the contract in 1899 for the U-Bahn and Berlin’s first underground station opened at Potsdamer Platz on the 18th of February, 1902.

As a result of new building techniques, the city’s underground was able to be used more intensively. Many office buildings and hotels that were built after the 1st World War in the inner city processed in addition to normal cellars, deep cellars in which technical equipment and storage rooms were located. Additionally, many owners had a second cellar level added to existing buildings. Already at that time, investors were forced to optimize the use their building plots for financial reasons. More effective use of Berlin’s underground was made possible almost everywhere by the use of modern building techniques involving the reduction of the ground water level.

Yet the development of Berlin was halted again and again by political and economic developments. The 1st World War and the Great Depression left its traces in the sandy underground in the form of incomplete tunnels. After the inflation of the 1920s was tackled, a tunnel boom commenced. Four new U-Bahn lines were brought on-line by 1930 and pre-existing lines were extended. For a planned U-Bahn line between Treptow and Moabit, building preparations were made at the stations Potsdamer Platz and Moritz Platz. Similarly, at Alexanderplatz “blind tunnels” were built for a planned U-Bahn between Weissensee and Steglitz. However, as a result of the Great Depression, these plans were halted and never realized.