Nine stainless steel clad spheres are connected so that the whole forms the shape of a unit cell of an iron crystal - magnified 165 billion times. It has been a landmark in Brussels since it was constructed for the 1958 World's Fair.

This impressive fortress towers above Edinburgh on Castle Hill. It is not only a landmark of the city but also one of Scotland's most important sights. Mary, Queen of Scots, resided here and gave birth to her only child before she was imprisoned and forced to abdicate.

The Charles Bridge is only ever this deserted early in the morning. It is, after all, one of Europe's most visited places and inundated with crowds during the day. At 516 meters (1,693 feet) it is the longest gothic stone bridge in Europe.

It was, and is, a key location when it comes to European history. As a symbol of German unity, it is recognized around the world. The Brandenburg Gate is Berlin's most photographed sight, closely followed in popularity by the adjacent Reichstag parliament building and government quarter.

Every ancient Greek city would have an acropolis, a citadel built on higher ground with temples and fortifications. But the Acropolis in Athens is world famous and one of the best-known ancient European sights. It has towered above the Greek city for over 3,000 years. In 1987, it was named a UNESCO World Heritage Site.

Red Square, located in the center of Moscow, boasts some immense proportions: 330 meters (1,082 feet) long and 70 meters (229 feet) across. It is lined with sights including St. Basil's Cathedral with its onion-shaped domes (pictured), the State Historical Museum, the GUM department store and Lenin's Mausoleum.

There are so many ancient sights in Rome, that the city is hard pushed to meet the demands to preserve and maintain them all. The Colosseum, however, has just undergone a major restoration. It is the world's biggest ancient amphitheater. The arena offered room for some 50,000 spectators, in a venue where centuries of gladiatorial battles were held.

It is probably the most famous construction site in the world. Work on the church designed by Antoni Gaudí commenced in 1882. To mark the 100th anniversary of Gaudi's death on June 7, 2026, the monumental building project is due to be completed. Today you can tour the church's fascinating interior.

For over 120 years, the iconic bascule bridge with its two 65-meter (213-foot) high towers has defined the London skyline. The Tower Bridge connects the city's northern and southern districts. The bridge, as well as the view of it on the Thames River, is a major tourist magnet for the British capital.

The Eiffel Tower represents Paris, the city of love, and even all of France. With 7 million tickets for admission sold annually, it is the most visited paid monument in the world. It is no wonder then that it also takes first place in the Instagram rankings.