Some colleagues from the Instituto de Arquitetos do Brasil – IAB (Brazilian Institute of Architects) and I spent some years organizing the 27th World Congress of Architects, initially planned to be held in July 2020 in Rio de Janeiro. However, the pandemic caught us along the way and we had to postpone the event until 2021. From March to July 2021, debates, conferences, lectures, exhibitions, films, and many other activities – almost all of them online – were carried out with hundreds of leading professionals and almost 100,000 participants from 195 countries. With such a diversity of prominent names, as we had intended, a unifying idea emerged: we are all together and it is up to us to contribute creating better, prettier, more climate-friendly, and less unequal cities. It did seem that the subject of the Congress (which was defined still in 2014, when Rio was elected as the host city) had been premonitory: "All the worlds. Just one world. Architecture 21". On the eve of his 100th birthday, French philosopher Edgar Morin drew attention to the possibility that the aftermath of the pandemic could give rise to new world-transforming forces, however fragile they might be. And that given this possibility, our path should be one of hope. This thought has inspired the World Congress of Architects and, somehow, also this book. I gathered a handful of texts and wrote a few others under the impact of the challenge to turn the 21st century into a more humane place. I state no thesis here, but rather a plea. I am very grateful to everyone who contributed to making this book a reality, starting from the initial (and continuous) motivation as offered to me by my dear Rosana Lanzelotte, from Musica Brasilis. I'd like to highlight the great performance of RioBooks' publisher Denise Corrêa, whom mycolleague Verena Andreatta had recommended me, and the competence of a few others: architect Anita Di Marco's in the thematic review of this volume; Sylvia Cardim's in the sophisticated graphic design; my friend and colleague André Luiz Pinto's in selecting and treating the images presented here; my dearest old friend and great artist Thereza Miranda's inspiration for the presentation of the book; and finally Victor Burton's in conceiving the book cover. In part, some of the ideas stated here resulted from special contributions by dear friends such as Fabiana Izaga, André Luiz Pinto, Eucanaã Ferraz, and Graça Matias Ferraz. Some topics were discussed in the creative environment of the Graduate Program in Urbanism at FAU UFRJ. I thank my children Pedro, Tiago, and Aninha, who took care of me with tenderness and understood my effort to conclude these texts. I owe a special thanks to the Rio de Janeiro city government and its Culture Department for promoting this book using the ISS Incentive Law, as well as to the sponsoring companies Grupo Globo, Icatu, and STX Empreendimentos. Both the book and I were extremely honored by the references made by Ruy Castro, Zuenir Ventura, and Luiz Fernando Janot, whom I thank in the hope of living up to their expectations. However, I count on their generosity and yours, dear reader, in understanding that this is but a small amount of mortar to help build better cities. It is hope!