A former waterfront market is now in the center of town due to some interesting Boston engineering.

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

A beautiful geyser under environmental threat.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

A five-square-mile slice of Spain on the Mediterranean coast of North Africa.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

An archeological treasure trove stumbled upon by a couple of children.

Giant topiary dog once played a role in a terrorist bomb plot.

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

The final resting place of the great navigator, or maybe his brother.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

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

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

A bright little alley in La Boca is a part of tango history.

A beautiful young girl said to have been buried alive in her coffin…

Abandoned bull fighting ring, slowly falling apart in Uruguay.

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

Mountain where Jesus was first tempted by the Devil.

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

The world's most elegant power lines.