Atomium

On the northern edge of the city, nine huge silver spheres hang in the air, joined by tubes, gleaming against the sky, a giant model of something microscopic blown up to the size of a building. This is the Atomium, Brussels' most futuristic landmark, built for a world's fair and never taken down.

The structure is a model of a crystal of iron, its atoms magnified many billions of times, with the spheres standing for the atoms and the tubes for the bonds between them. It was a bold symbol of a scientific, atomic age, and of faith in progress.

It was built for the world's fair held in the city in 1958, one of the great optimistic expositions of its era, and proved so popular that, unlike most fair buildings, it was kept and has become a permanent symbol of the city.

Visitors travel up and through the structure, by lift and escalators within the tubes, moving between the spheres, several of which hold exhibitions on the fair, the building, and design, so the inside is as much an experience as the outside.

The top sphere holds a viewing level and a restaurant, giving wide views over the city and the surrounding parkland, with the spheres of the structure framing the outlook in a way found nowhere else.

The stainless-steel skin, renewed in a restoration, gleams in the sun and reflects the sky and clouds, so the structure changes with the light and the weather, and its strange silver shapes are endlessly photogenic.

The Atomium stands in a park on the edge of the city, beside a popular attraction where the great buildings of Europe are recreated in miniature, so the two are often visited together as a family day out.

It is, frankly, a piece of mid-century optimism and spectacle rather than ancient history, but its sheer oddness and ambition, and the views from the top, make it one of the city's essential sights.

The structure is lit at night, the spheres glowing and twinkling, so it has a different character after dark, visible from across the northern districts of the city.

Reaching it is easy by the city's metro to the edge of the park, and the approach across the open ground, with the spheres growing ahead of you, builds the sense of arriving at something from the future.

A few practical notes. Entry is ticketed; book ahead in busy periods, and choose a clear day for the views from the top sphere. It sits a little outside the centre, easily reached by metro, and pairs with the miniature-Europe park nearby.

Ride up through the tubes into the spheres, look out over the city from the top, and the strange ambition of a building shaped like a magnified crystal makes its own kind of sense. When you cross the park back to the metro, the silver spheres hang behind you, a piece of the future left standing.