Medicinal spa created with the discharge from a geothermal energy plant.

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

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Once the home of a hermetic monk, this cave now houses a small church.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A striking symbol of the Bulgarian capital.

"Holy Wisdom" overlooks the city that became its namesake.

A vast Communist-era exhibition space in the Bulgarian capital.

An ancient necropolis of magnificent tombs.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

Trek up this glacier before it disappears.

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

The granddaddy of English geoglyphs dates back to the late Bronze Age.

The highest peak in all of England is plagued by dangerously fickle climate shifts.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

These 20-foot jaw bones honor a time when the leviathan bones were a sign that whalers survived the hunt.

This ancient bridge made of stone slabs is said to be reserved for the devil to sunbathe.

This striking observation tower shaped like a spinnaker sail is the newest icon in historic Portsmouth.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.