was removed to allow for excavations for the new S-Bahn underground line. On 26 September 1997, a replica of the tower was erected, just for show, close to its original location by Siemens, to celebrate the company's 150th anniversary. The replica was moved again on 29 September 2000, to the place where it stands today. The traffic problems that had blighted Potsdamer Platz for decades continued to be a big headache, despite the new lights, and these led to a strong desire to solve them once and for all. By now Berlin was a major centre of innovation in many different fields including architecture. In addition, the city's colossal pace of change (compared by some to that of Chicago), had caused its chief planner, Martin Wagner (1885–1957), to foresee the entire centre being made over totally as often as every 25 years. These factors combined to produce some far more radical and futuristic plans for Potsdamer Platz in the late 1920s and early 1930s, especially around 1928–9, when the creative fervour was at its peak. On the cards was an almost total redevelopment of the area. One design submitted by Wagner himself comprised an array of gleaming new buildings arranged around a vast multi-level system of fly-overs and underpasses, with a huge glass-roofed circular car-park in the middle. Unfortunately the worldwide Great Depression of the time, triggered by the Wall Street Crash of 1929, meant that most of the plans remained on the drawing board. However, in Germany this depression was virtually a continuation of an economic morass that had blighted the country since the end of World War I, partly the result of the war reparations the country had been made to pay, and this morass had brought about the closure and demolition of the Grand Hotel Belle Vue, on the corner of Bellevuestrasse and Königgrätzer Strasse, thus enabling one revolutionary new building to struggle through to reality despite considerable financial odds. Columbushaus was the result of a plan by the French retail company Galeries Lafayette, whose flagship store was the legendary Galeries Lafayette in Paris, to open a counterpart in Berlin, on the Grand Hotel Belle Vue's former site, but financial worries made them pull out. Undaunted, the architect, Erich Mendelsohn (1887–1953), erected vast advertising boards around the perimeter of the site, and the revenue generated by these enabled him to proceed with the development anyway. Columbushaus was