Ancient paintings known as the "Sistine Chapel of Cave Art."

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

This massive blockhead sculpture hides an entire library.

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

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A more chill but no less fascinating version of the famous ancient archeological site.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

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."

This architecturally eclectic early-20th century mosque was built as a place of worship for the Islamic followers of a Jewish messiah.

Swarms of dainty flying insects swarm into the Petaloudes Valley to get busy.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

The ancient latrines of the Greeks, in all their public glory.

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

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

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

This former Imperial summer home was the venue for a royal slap that once echoed 'round the world.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

Step back in time and witness the fall of Constantinople.

Ancient serpentine sacrifice holder that has stood the test of time.