This irregularly shaped sea fortress has defended not one but three different sovereign states.

According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

This local emblem is the oldest and largest dragon tree in the Canary Islands.

A large collection of solar and night-time telescopes dot a small area on the Teide mountain range.

A unique bridge with an equally unique view.

This towering church is home to a world-famous organ and a treasure trove of medieval art.

An idyllic hotel that gave its name to a supposed shadow government.

The tallest mountain in mainland Netherlands isn't actually very tall.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

This 600-year-old home seems to defy physics.

Its town washed away centuries ago, this lonely tower by the sea tells the tale of a mermaid and a curse.

Watch the local Netherlands birds from inside this giant eco-egg.

A unique military outpost carved into a rocky outcrop in the English Channel.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

This beautiful, historic church looks like something out of a simpler past.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

Inside this Icelandic greenhouse, geothermal energy keeps tomatoes warm and growing.

Along this wire fence, travelers have been leaving a particular memento since 2012.

Iceland's tribute to its thankless civil servants.

The largest whale museum in Europe allows visitors to walk among life-size giants.

This large sand dune in the Netherlands is home to wind-whipped trees with "floating" roots.

While most bridges allow roads to pass over water, this one allows water to pass over a road.