This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Monasteries on rock pillars, once accessible only by frayed ropes.

The hallucinogenic center of the ancient world.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

These waste baskets play a few risque messages to discourage littering.

A centuries-old iron mine is now a paradise for explorers, divers, and spelunkers.

The official meeting point for the oddly named governing assembly of ancient Sweden.

Gravity seems to fail at this intriguing Swedish attraction.

Ancient stone graves shaped like ships provided a Viking-like burial to carry the dead to the afterlife.

This fantastic cave remained unexplored until 1948 when three schoolboys discovered a hidden entrance.

This castle ruin in the middle of nowhere is a gem for wildlife enthusiasts.

Iron Age grave stones and Viking burials, a short drive from Gothenburg.

Stockholm's narrowest alley is barely over two feet wide.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

Stepping inside this coffee shop is a journey through time.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

At the most northwestern point of the contiguous United States lies a trail leading through an ancient forest to stunning cliff-side vistas and massive oceanside caves.

A French valley with forests so lush it was nicknamed "the Small Amazonia of the Pyrenees."

The eerie remnants of an ancient forest were hidden under the sand for centuries.