People keep on asking me whether commissioning a big, glamorous new building will "brand" their city. It seems to be the question of the month among city governments.
The answer is that it depends why you're doing it, and how original the building really, objectively is. If the building is highly expressive of something clear and interesting that your city is telling the world about itself - like the Guggenheim Museum in Bilbao, the Sydney Opera House or the Kunsthaus in Graz - then it might be a very effective piece of 'branding' (although it will achieve nothing on its own - it has to be one well-chosen part of a very long term series of substantial actions that make the story real). If, on the other hand, it's done for its own sake and there's no real long-term strategy behind it, it will add nothing to the city's overall image at all.
Most 'trophy buildings' aren't expressive of anything in particular: they are just very large glass and steel filing-cabinets which, if they communicate anything at all, are simply monuments to money, power, modernity, technology, and the desire to show off. You need a veritable forest of such buildings before they really mean anything - and that meaning is only how much money there is in your city.
"Make me a landmark building" is no kind of brief for an architect: but "tell the world our story" might be. Buildings must say something about their city and the country, or they are just bricks and mortar. Or steel and glass.