"Cities, like dreams, are made of desires and fears, even if the thread of their discourse is secret, their rules are absurd, their perspectives deceitful, and everything conceals something else." - Italo Calvino, Invisible Cities


The culture of cities has always been as complex, contradictory, cruel, and wondrous as the general blend of darkness and light manifested by our species as a whole. As the metropolis has grown to a hundred thousand, a million, twenty million inhabitants—with just as many "dreams made of desires and fears"—the culture of cities has, to different degrees, offset this chaotic diversity and binds together the inhabitants of urban places in life-affirming common purpose.

In this book I ask why some cities preserve their heritage better or more readily than others. My years of investigation have shown that the most truthful, all-encompassing, and succinct answer to this question is that a sensitivity to conservation has evolved in their culture. There are of course specific legal, economic, historical, social, political, and physical circumstances involved in this question, but their complex interrelationship can only be described as cultural. Preservation is different in different places because the culture of every great city is unique. And in our age of globalization and creeping homogeneity, it is exactly this uniqueness that is in need of saving.

The culture of cities is both visible and invisible, palpable and elusive. On the one hand, we know the culture of urban environments from the experience of being in them. Paris feels like Paris and noplace else, just as the smells, sounds, sights, aura, and rhythms of life in Beijing, Amsterdam, Kyoto, Venice, Jerusalem, and Mexico City become singularly etched in our memories after just one visit. Yet while we may recognize the cultures of different places, we cannot quantify any particular culture in exact terms, in part because a city's culture is always evolving—growing out of the past and changing at the moment we attempt to define it.

In response to this dilemma, my work on this book became, in part, a search for the genesis of the conservation impulse, for moments when the significance of saving urban culture was crystallized. Nonetheless, I was somewhat shocked when I found that just such a decisive confirmation of the tangible significance of historic buildings was activated by none other than Adolf Hitler during World War II, when in order to subdue the Poles he ordered the destruction of the monuments of Warsaw. In seeking to destroy his enemies' courage, Hitler identified a primal source of their strength.

Three decades later, in Invisible Cities, Italo Calvino showed the meaning of the culture of cities to an equally decisive degree, by writing about imaginary urban places in poetic prose and capturing the essence of urban identity through metaphors. In order to solve the similar problem of making comprehensible the contradictions of cities, where often "the thread of their discourse is secret, their rules are absurd, their perspectives deceitful, and everything conceals something else," I have chosen to write about the drama of urban conservation by identifying important moments in history when human events culminated in a clear clash of values—when common sense, logic, law, and sometimes even the principles of physics were defied. And because the corporeal material of the metropolis is one of the elements that tie a city's people by invisible threads to the past, I have endeavored to set such moments in the context of each city's history, in urban profiles, so that tensions among cultural values can be seen in terms of cultural evolution. The preservation of great cities is ultimately the story of how different urban societies created environments of extraordinary meaning, were affected by their cityscapes through centuries of habitation, and came to realize that the loss of old buildings involved much more than just the vis-ible destruction of ancient bricks and stones.