A propos of a project of tube redevelopment in Camden Town, Tom Coates asks if it is more important to preserve the identity of a city or to look to the future:
should they have tried to preserve some of the facade of the old underground in some way, or is that just nostalgia?
I don't know how to define the identity of a city, for this seems to be subjective and probably encompassing a lot of different notions to different people. For example, its inhabitants mood, pace, commerce, traffic... many things can shape it. I will focus on the architecture (which includes urban design), because it is probably the most compelling element in the perception one has about a city's identity. It is also, I think, the central element in Tom's question.
As a citizen of Paris, I tend to think of the identities of neighborhoods rather than a single identity for the entire city. Once you start to perceive the distinctive elements of Paris' quartiers, you can really think of this city as a juxtaposition of villages. However, Paris is one example of a city that has done a rather good job at preserving its architectural traits, the general consensus now being to preserve existing neighborhoods (the city is busy building a couple of new ones, so it can afford a playground for modernity). But this has not always been the case and one of the oldest constructions, les arènes de Lutèce (a roman amphitheater built around the Ist century in the gallo-roman city which preceded Paris), rediscovered in 1869, was partially demolished around 1880 to build... a bus terminal! In 1883, Victor Hugo wrote to the municipal council:
It is not possible that Paris the city of the future renounces to the living proof that it has been the city of the past. The past leads to the future. The arènes are the antique marks of a great city. They are a unique monument. The municipal council which would destroy them would, in some way, destroy itself. Save the arènes de Lutèce. Save them at all costs. You will do a useful action and, which is better, you will give a great example.
Hugo succeeded to convince the municipal council, which bought the terrain, classified the arènes as a historical monument and eventually did a partial restoration. The public voice (if Victor Hugo can be depicted as the public voice) spoke up in defense of something that was not deemed important at the time: the preservation of a city's heritage.
A striking counter example of city that has, apparently, some problems to preserve its identity is Brussels. If there is such thing as architectural liberalism, it has its European headquarters there. The city of Brussels has allowed the destruction of entire residential boroughs that had their own identity, to build huge business areas. Those areas did not lift off economically and were eventually "returned" to their residential destination. Unfortunately, by the time, their identity had been destroyed and no one would want to live there. As for the creation of a new identity, it seems that anyone is allowed to build anything anywhere in the city, preventing the emergence of a style, or styles within a consistent urban design. I would certainly not say that Brussels has no identity, but its architecture is a pandemonium where the best borders on the worst.
Is London in better shape than Brussels? I would think so. However through what Tom writes and my own trips over the tunnel sous la Manche, it seems that the virus of architectural liberalism has caught London in some way.
Back to Tom's question, are we in a dilemma of nostalgia vs. modernity? I see no reason why preserving the past would jeopardize the future or, more exactly, the evolution of a city's identity. But this requires some efforts and a public consciousness, very much like Victor Hugo did 120 years ago. Architecture, like music or a foreign language, reveals its inner beauty to those who are able to decipher it, and with the effort of learning comes the pleasure of being able to understand and appreciate where we come from, where we are now and, for the most creative, what possible new paths have a chance to last in our identity. Without this, the natural tendency is to destroy and rebuild, to escape a present we are uncomfortable with and a past we cannot understand. I am also a strong believer that preserving the past, far from being nostalgia, provides a great emulation to those who aim at creating our future. Taking Paris as an example (I hope you don't mind, you can transpose that to another city), try to find the architectural styles born less than a century ago that have the creative strength, impact, influence on the city that have the 1900 (école de Nancy, e.g. Guimard and his famous subway entrances) and the Haussmannian styles. There are a few candidates of course, but how would we know without the living proofs of the past?