An ancient underground cultic temple where sunlight penetrates on the summer solstice.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.

The National Railway Museum in York is the largest railway museum in the world, attracting almost 1 million visitors per year.

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

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

An array of ancient artifacts from Bronze Age Bristol and other civilizations are housed in this museum.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

Journey through this open museum where even employees remain true to period.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

A lush indoor jungle fills this bustling Madrid transportation hub.

Commonly acknowledged as the only public monument to the Devil himself.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

An ancient Egyptian temple in the middle of Madrid, Spain.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

The building where Mary, Queen of Scots was said to have bathed in white wine.

The fountain marks the area where hundreds of accused witches were burned at the stake.

Largest lake in Great Britain measured by surface area.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.