The commemorative stone column conceals a secret laboratory.

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

This line of 12 tower mills described in the story of Don Quixote is among the most iconic landscapes in Spain.

The world's largest wooden structure.

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

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

Moorish signal station on a stratgic rocky outcrop.

A Spanish town built into the cliffs.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Single runway interrupted by a busy road that cuts across its middle.

A hidden three-foot-wide house separates these two regal churches.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Elaborate tile work in this railway station tells the story of Portugal.

An exquisite collection of fairytale conveyances that puts most car museums to shame.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

Sip cherry liqueur at a bar dating back to 1840.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The picturesque remains of an abandoned silver mine slope down to Tagish Lake in the Yukon.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.

A whale of a public art display towers atop Juneau's cruise ship dock.

A historic area for shopping and dining in Ketchikan's former red-light district.