"Often disorder, if observed methodically, contains its own explanation."

The reading of the changes underway at the edges of contemporary cities is one of the most difficult subjects to tackle methodically.
Proof of this is the descriptive literature produced on the topic.
The obvious obstacle is that the forms in which expansion takes place continuously evolve in time and space.
The Conzenian school offered a clear interpretation of these phenomena, attempting to generalise instances of interpretation developed for individual cities.
In the wake of Saverio Muratori teachings, Caniggian school too provided us with a theoretical model of the forms of urban expansion.
More recently other concepts emerged, as the rural-urban fringe (R-U fringe), understood to mean the transitional zone that, in Western cities, indicates a discontinuous territory and a contradictory landscape on the border between city and countryside.
This book compares and contrasts a number of essays on urban expansion that examine case studies located in various different geographic areas: from Europe to Asia, from North to South America.
What interests the editor is to compare interpretational models derived from experience that come under the umbrella of Urban Morphology, developed in different cultural contexts that nevertheless share the conviction that the form of a city, even in its most seemingly chaotic incarnations, can be interpreted rationally and contains the seeds of future change.

Giuseppe Strappa is an architect and full professor in Architectural and Urban Design, director of PhD School of Architecture and Construction and Lpa Reading and Design Laboratory of the Sapienza University of Rome. He is also carrying on research on the fields of urban morphology and cities transformations.