A series of waterfalls create the illusion of perpetual rainfall in this hidden gorge.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

Legend says it was constructed with the destroyed pillar of an ancient Greek Temple.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

Barcelona's only remaining tram system takes riders to the Tibidabo funicular.

This urban park is home to monkeys and a number of endangered plants.

In the Monastery of São Vicente resides a gallery devoted to a breathtaking collection of seashells.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Commemorating the 1948 creation of the Jimmy Fund, a Boston-based cancer charity.

This hotel was the site of major events in sports and radio history. It was also used as a detention center during World War II.

A school used as a model for public education across the country.

A plaque marking the famous abolitionist's birthplace often overlooked by visitors to the nearby Charles Sumner House.

In the 19th century, this was the center of Boston's Black community.

Around 160 years ago, this spot marked the location of a wharf along the shores of the Charles River.

A real plaque marks the spot where a Faulknerian character committed fictional suicide.

Dedicated to one of the darkest moments in Irish history, this memorial has faced its fair share of backlash.

The oldest working bell set in North America, the bells at Old North Church sat silent for their first four years in Massachusetts.

This historic patch of real estate offers a glimpse of colonial Boston.

Historic Hull Street was actually the first street with a proper name in the Boston area.

The remnants of a Gilded Age elegance preserved in the middle of a stark modern tower.