Vienna has been inhabited at least since the days of the Romans. It was already a metropolis in those days but the face of the city changed repeatedly over the centuries. You can still imagine the glories of the past centuries in the Viennese old town.
Rigidly followed laws concerning the protection of monuments by government offices have made it possible to admire buildings from various cultural periods. While these buildings are meticulously restored, they don't turn into museums. People still inhabit and work in the elegant city palaces and middle class houses; government offices and institutions have taken over the splendid historical buildings of the city.