This once-forgotten oasis in the middle of Lisbon was first created over a century ago quite by accident.

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

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This charming candle shop has been in business since 1789.

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

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

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

Houses are tucked between, on, and underneath giant boulders.

Strange rumors surround the artist who created these solemn metal guard dogs.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

The figure atop this globe is from a Serbian play about a merchant's travels around the world.

At this archaeological site, visitors can explore the ruins of the capital of the former Roman province of Moesia.

Housed in a 1912 architectural masterpiece, this outlet of the Golden Arches is a real beauty.

Stone age urban planning.

A Roman monument to their own civil engineering prowess.

The ridged layers that make up this river canyon represent Earth's geological history.

Through the colossal entrance to this cave you'll find limestone tubs and an underground waterfall.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

The hairpin turns in this mountain road take the shape of a letter—is it a coincidence or a symbol of love?

The only known mosaic depicting the Greek god of sleep, Hypnos.

This historic observatory contains the world's oldest refracting lens telescope.