This book takes readers on a guided tour of CERN (the European Organization for Nuclear Research), revealing the fascinating inside story of the world's largest particle physics laboratory. Along the way, readers will discover how CERN came into being, how its vast machines work, what scientists do there every day, and the groundbreaking discoveries that have transformed our understanding of the universe, as well as what lies ahead for the future. Written by a former CERN engineer and an experienced official guide, the book makes the science behind these discoveries accessible and engaging, answering the many questions that naturally arise among scientifically curious visitors. Richly illustrated and written with clarity and enthusiasm, it is an ideal introduction for anyone taking their first step into the fascinating world of high-energy physics and CERN.