The Atomium is the futuristic symbol of Brussels, a giant 102-metre model of an iron crystal built for the 1958 World Expo, its nine gleaming spheres connected by tubes. A ticketed visit lets guests ride escalators and a lift through the structure to exhibitions and a panoramic sphere with sweeping views over the city. A bold icon of mid-century optimism and design, both surreal and impressive up close, it is one of Brussels’ most distinctive landmarks and a must-see, especially memorable when lit up after dark.