We wanted to circulate a text on the city that would be accessible to undergraduate students, and this obliged us to use accessible language and to minimise excessively specialised lexis (slangs), unnecessary Anglicisms and excessively abstract formulations and/or formulations expressed in mathematical language. But we also had the risky intention of approaching the city as an object of study and not as a field of application of this or that discipline. We intended to approach the fact of the city – our urban planet – in a relatively holistic, multidisciplinary or, if you like, transversal way, as far as our knowledge would allow, even making some suggestions about the great contribution made to the knowledge of the city by other subjects that were and are outside our field, such as literature, painting, photography or cinema, to cite just a few examples. The text, therefore, was and is intended to be useful for students of disciplines that are close but at the same time distant (economics, history, geography, tourism, sociology, political science, environmental sciences and even architecture) and this, as well as being reflected in the title of the work, required us to make a further effort to be clear. And, of course, we could try to make the text comprehensible to the interested public. We would necessarily lose in depth, but we would gain quite a lot in the unavoidable function of cultural dissemination of a subject as popular as it is mistreated due to an excess of disciplinary fragmentation. An additional decision was to avoid the temptation of offering a closed text with only answers and no questions. This explains the presence of the “questions for debate” section in each thematic block.