Atomium

The Atomium is a 102-metre-tall model of an iron crystal magnified 165 billion times — built as the centrepiece of the 1958 World Expo and intended to be temporary, but so beloved by Brusselaars that demolishing it became politically impossible. The nine interconnected spheres, connected by tubes containing escalators and staircases, represent the atoms of a body-centred cubic iron crystal, and the entire structure is clad in stainless steel that reflects the Belgian sky in a way that makes the building look different every hour.

The top sphere contains a panoramic restaurant with views across Brussels and the surrounding Brabant countryside — on a clear day, you can see the towers of Antwerp to the north. The connecting tubes house exhibition spaces and a corridor with light installations that feel like walking through a science fiction film set. The lowest sphere hosts temporary exhibitions and the ticketing area. The overall experience — riding escalators through tubes between enormous silver balls suspended 50 metres in the air — is unlike anything else in any city.

The Atomium sits in the Heysel/Laeken district, adjacent to the Mini-Europe park and the Royal Domain of Laeken (the Belgian royal family's residence). The surrounding parkland provides excellent vantage points for photographing the structure, and the reflection of the spheres in the surrounding pools at sunset is one of Brussels' most photogenic moments. The Atomium was designed by André Waterkeyn and renovated extensively in 2006, replacing the original aluminium cladding with stainless steel.