One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

A historic observatory now an astronomy museum beautifully situated at the moat of the Middle Age city centre.

The world's largest bicycle shelter can hold more than 12,500 two-wheelers.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

The location of the world's first telescope demonstration.

Liechtenstein's royal family calls this medieval alpine castle home.

Cages that once displayed the bodies of executed leaders hang from a German church tower.

As the Dead Sea continues to deplete, massive sinkholes open along its banks.

A "miracle" that seems to produce more holy fistfights than holy revelations.

Oldest Protestant church in the Middle East, designed to resemble a synagogue.

The only quarter of the Old City not dedicated to a major world religion.

A deadly ancient portal to the underworld.

The ancient latrines of the Greeks, in all their public glory.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

This is the oldest Roman-made bridge in the city still existing in its original state.

A retirement home for soldiers that can trace its history to the Elizabethan era and beyond.

Believed to be inspired by the Trevi Fountain in Rome.

One of the oldest Masonic buildings in England, and still in use today.

A 15th-century Corsican chapel that possesses a rare Catholic monument: a "Scala Santa," or "Holy Stairs."

This memorial, built by fascist dictator General Franco in 1960, has been repurposed by the people of Catalonia.

This Roman arena once played host to bloody gladiatorial battles.

Touching the iron railings of Tarragona's balcony to the Mediterranean is said to bring good luck.