During the Industrial Revolution, many factories and railway lines were built in Frankfurt and its suburbs. In the city centre, a lot of big buildings were built, like an opera house, theatres, stock exchange, railway stations, department stores or museums. Tram lines were constructed to make travelling inside the growing city easier. In World War II, the old city was totally destroyed by airplane bomber attacks. After the war, Germany was divided into two parts, and Frankfurt became the economic capital of West Germany while Bonn was chosen to be the political capital.