Tour the inside of a massive lava tube formed during a 1949 volcanic eruption.

This panoramic lift provides a futuristic ride up San Pedro Mountain.

A wonderful collection of fossilized dinosaurs and other creatures that roamed the landscape millions of years ago.

A somewhat mysterious biomedical museum housed inside a Spanish university.

A reproduction of the famous prehistoric cave paintings is hidden underground at the National Archaeological Museum.

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

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

You can soak in three relaxing pools filled daily by the tide.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

The largest medieval water tank on the Iberian Peninsula is preserved beneath the Cáceres Museum.

In Spain, the ruins of a Roman military camp sit along a flooded section of a river.

This 19th-century fountain's namesake animal isn't what you think it is.

Stormy conditions send jets of seawater bursting through holes in the cliffs.

This underwater graveyard commemorates a group of murdered 16th-century missionaries.

The unexpectedly beloved remnants of a controversial thermal power plant.

A well-restored ancient archaeology site gives a real feel for life during the Roman age.

The largest prehistoric cemetery on the Balearic Islands dates back over 2,500 years.

An outsider folly near Madrid.

A historic Christian shrine nestled within a spectacular natural cave.

Translating as "The Jump of the Girlfriend," this stunning waterfall has a tragic legend behind it.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

This enchanting hamlet carved into the rock looks like something straight out of Tolkien's Rivendell.

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