by British architect Richard Rogers. The Berlin Senate then chose to divide the area into four parts, each to be sold to a commercial investor, who then planned new construction according to Hilmer & Sattler's masterplan. During the building phase Potsdamer Platz was the largest building site in Europe. While the resulting development is impressive in its scale and confidence, the quality of its architecture has been praised and criticised in almost equal measure. Daimler The largest of the four parts went to Daimler-Benz, who charged Italian architect Renzo Piano with creating an overall design for their scheme while sticking to the underlying requirements of Hilmer & Sattler's masterplan. A $2 billion development bordering the west side of the former Potsdamer Bahnhof site, some of its 19 individual buildings were then erected by other architects, who submitted their own designs while maintaining Piano's key elements. The primary materials used for the buildings' facades are brick, terra cotta and sandstone, creating hues of beige, soft brown and ocher. The first spade at the start of the Daimler-Benz development was turned by the Mayor of Berlin, Eberhard Diepgen, on 11 October 1993. During construction, the contractors erected a bright red three-story building called the Info Box, where computer graphics help convey the scope of one of the most complex building projects ever attempted; it quickly became a highly popular attraction with thousands of visitors each week. The finished complex was officially opened by the Federal President of Germany, Roman Herzog, on 2 October 1998, in a glittering ceremony featuring large-scale celebrations and musical performances. The 19 buildings include the offices of Daimler-Benz themselves (through their former subsidiary debis, whose 21-storey main tower rises to 106 metres and is the tallest building in the new Potsdamer Platz development), also offices of British professional services company PricewaterhouseCoopers; Berliner Volksbank (Germany's largest cooperative bank) by Arata Isozaki; a five-star hotel designed by Rafael Moneo and managed by Hyatt, with 342 rooms and suites; and the 25-storey, 103-metre-high Potsdamer Platz No. 1, known as the Kollhoff Tower by architect Hans Kollhoff. Potsdamer Platz No. 1 also houses the "Panoramapunkt" viewing platform, located 100 m above ground level, which is accessed by riding Europe's fastest elevator (8.65 metres per second). From the Panoramapunkt one can see such landmarks as the Brandenburg Gate, Reichstag, Federal Chancellery, Bellevue Palace, Cathedral, Television Tower, Gendarmes Market, Holocaust Memorial and Kaiser Wilhelm