The exterior of the Sony Center is dominated by the Bahn Tower, the glass headquarters of Deutsche Bahn, the state railway company. But it's the interior of this glass and steel complex designed by Helmut Jahn which is particularly impressive. The 4 000m2 space adorned with a spectacular capital is a true feat of technology. The surrounding buildings shoulder a massive ring bearing a slightly angled mast, which in turn supports the glass fibre capital.