A remarkably intact castle that once was the largest in Ireland.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

The modern birthplace of Irish freedom.

Three columns of volcanic rock shoot out of the ocean.

The history of Greece is illustrated through banknotes.

One of the most photographed locations in the entire city.

Legend says this sacred tree was a gift from goddess Athena.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

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

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

In the waters outside Helsinki, a tiny island once used as a military outpost now welcomes visitors.

These enormous, stern-faced statues greet visitors with lanterns, and sometimes costumes.

Finnish lake, and scene of an infamous murder mystery.

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

This dizzying tower was built to better broadcast the 1980 Moscow Olympics.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Copenhagen's celebrated theme park and gardens.

A church of bones, decorated with 40,000 human skeletons.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.