Britain's answer to the NSA is based out of this deliciously-named circular headquarters.

The largest greenhouse in the world is home to over one million types of plants.

Pop culture has helped to keep this iconic British building from being destroyed.

London's old-school healing garden.

Eighty million natural history specimens call this gargantuan museum home.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The bears of Bern have been a city highlight for over 500 years.

This simple apartment may have inspired some of the most important theories in the history of science.

Looming communist pillar with a Czech twist.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Macabre astrological automaton clock dating to the late 1400s.

Where the lovelorn find a home for their sentimental keepsakes.

Tucked away near more famous landmarks lies a statue meant to symbolize the confluence and continuing development of human culture.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

One of the most controversial statues in Romania is an emperor with no clothes.

Romania's triumphal arch looks out over Bucharest.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.