Every day about two million passengers squeeze into Berlin's buses and trains. But how did the subway and tram lines emerge as an important part of public transport more than 140 years ago? In the historic control center at the Olympia Stadium subway station, the Berlin Underground Museum provides a glimpse of the history, progress, and current operations of the subway system. In 1881, Siemens developed the world's first electric tram and launched it in Lichterfelde, a suburb of Berlin at the time. "The Electric" soon became an integral part of the city. As the population grew rapidly at the end of the 19th century, there was an increasing demand for innovations in transport systems. In the meantime, Berlin had become an aspiring industrial hub, with streets filled with horse-drawn carriages, trams and pedestrians. To solve the problem, routes would be built underground as well as raised above the streets on pedestals. The Berlin underground was one of the first projects of its kind in Germany. The museum provides a hands-on experience of many historic artefacts commemorating one century of underground history. Volunteers will answer all questions of both children and adults. Several times a year, special trips offer insights into some of the most impressive historical vehicles in the collection.