September 11, 2001, began like any ordinary Tuesday. The sky was clear over New York, Washington D.C., and Pennsylvania. Millions of people started their day without imagining that, within minutes, history would take a brutal and irreversible turn. At 8:46 a.m., the first plane crashed into the North Tower of the World Trade Center. Seventeen minutes later, the second impact transformed disbelief into certainty: the world was witnessing a coordinated, premeditated, and devastating attack.

That day, nearly three thousand people died on U.S. soil. But the impact of 9/11 extended far beyond the rubble, the smoke, or the immediate terror. What fell that morning were not just two towers, but the false sense of invulnerability of a superpower. And with it, the global balance that had prevailed since the end of the Cold War. From that moment on, the world entered a new era-one marked by the war on terror, the curtailment of civil liberties, the reshaping of geopolitical power, and the resurgence of old hatreds.

This book is not merely a reconstruction of events. It is a deep analysis of their causes, consequences, and contradictions. We examine how a relatively small jihadist network managed to alter the course of global politics, how governments responded-sometimes justly, at other times excessively-and how fear became a defining force of the 21st century.

9/11: The Day the World Changed invites us to look back, not with nostalgia, but with urgency. Because the decisions made in the days and years after 9/11 continue to shape our present: from conflicts in the Middle East to digital surveillance, from cultural polarization to the ongoing debate about the role of the West in the world. To understand that day is to understand why the world is the way it is today.

This is not just a book about terrorism. It is a book about humanity, about mistakes, about clashing ideologies, about pain and resilience. It is an attempt to make sense of a tragedy that still echoes through the cracks of history.

• Terrorism - Terrorismo

• Hijacking - Secuestro (de aviones)

• Twin Towers - Torres Gemelas

• Ground Zero - Zona cero

• First responders - Primeros socorristas

• Al-Qaeda - Al Qaeda (grupo terrorista responsable)

• Patriotism - Patriotismo