Erroneously called the world's tallest flagpole, this landmark is devoted to "good neighborliness."

A hand-built folk art installation covered with messages of God's love.

Burping, gurgling geothermal mud pots by the Salton Sea.

The ghostly remains of an accidental sea.

Believed to be the only Orthodox church in the world that features a free-standing pulpit.

The hallucinogenic center of the ancient world.

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

The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

Legend says this sacred tree was a gift from goddess Athena.

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

An ancient octagonal weather station named for the eight Greek gods of wind.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

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

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

A small troop of Japanese macaques live peacefully in the heart of this Tasmanian city.

This nondescript tunnel has been featured in a number of iconic movies, from “Roger Rabbit” to “Back to the Future.”

A Lovecraftian altar of nightmarish bronze chairs sits ominously on a boardwalk in Puerto Vallarta.

The menacing creature had a tremendous influence on the local culture before being exposed as a hoax.

The only example of a Paris Métro sign in use at a subway station outside of the French capital. 

A massive Montreal stadium that has seen nothing but trouble since its inception.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

A music-filled, booze-soaked oasis in the desert.