Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

An autonomous republic of Orthodox monks.

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

This legendary city has been a tourist attraction for centuries.

The hallucinogenic center of the ancient world.

This massive piece of aviation history calls this residential neighborhood home.

A collection of old steam and diesel locomotives sitting in a fenced-off garden.

Hidden treasures belonging to Mongolia's most revered and multi-talented monk spent decades buried in the Gobi desert.

Thousands of artifacts tell Mongolia's military history, from the Bronze Age to the present.

A jagged silhouette of shamanistic stone heaps rises from the shore of this dazzling mile-high lake.

Dinosaur eggs were first discovered at these fiery red cliffs.

An exceptional assortment of fossils recovered from private collections.

Mongolian Buddhists believe this monastery in the Gobi desert to be the center of the world's spiritual energy.

This spiritual landmark for practicers of Shamanism is drenched in milk and vodka and covered in blue scarves.

A huge communist-era propaganda monument and mural that offers stunning views of the Mongolian capital.

The oldest Buddhist monastery in Mongolia has survived centuries of invasions, political shifts, and religious purges.

Enormous statue of the Emperor of the Mongols.

The grassy landscape is home to the world's last truly wild horses.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

An ethereal glowing blue ocean cave in Croatia.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

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

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

A garden of flying flowers.