Peek into a cave of giant, glimmering crystals.

This much reformed Modernist building will be of interest to fans of contemporary architecture too.

This amazing cathedral was built on the site of the first Marian shrine in Spain and is important to Spanish speakers the world over

A young Gustave Eiffel assisted in the construction of this skinny metal observation tower.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

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

A medieval church with largest and oldest collection of Renaissance frescoes in France.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

A medieval shrine set into a towering canyon wall.

12th-century holy complex shares land with a natural park full of heavenly waterfalls and raptors.

Beneath the city of Lourdes, France is a massive, concrete church.

Hindu temple of the dead home to hundreds of long-tailed macaques.

A sprawling nature preserve harbors the world's only living dragons.

Once home to Komodo dragons, this island dreamscape has a rare combination of white, pink, and black sand beaches.

Anonymously sculpted and donated, these sculptures made from poetry books and pages are sprinkled around the city.

Of five volcanoes located in the massive Tengger caldera, this cone is the youngest and most active.

Subterranean place of worship in Indonesia.

One of Indonesia's tallest, this waterfall takes a 390-foot plunge into the Lake Toba caldera.

Site of the largest volcanic eruption in the last 25 million years, one which may have nearly wiped out humanity altogether.

An Indonesian mosque styled after St. Basil's Cathedral.

This massive complex is made up of hundreds of smaller temples that date back to the ninth century.

Hundreds of Buddhas in a re-discovered Indonesian temple.

A Spanish town built into the cliffs.

Colorful and chaotic stacked hotel in North Holland.