This tree was grafted from the actual tree that led Isaac Newton to ponder the theory of gravity.

This 18th-century sundial was designed to calculate the date of Easter each year.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

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

Macabre astrological automaton clock dating to the late 1400s.

A church of bones, decorated with 40,000 human skeletons.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

Gargoyle head that brings good luck.

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

This historic timepiece is thought to be the only public clock in the world that keeps lunar time.

A number of craters left by fatal mortar strikes have been filled with red resin to remember those lost during the Siege of Sarajevo.

Oriental bazaar in the heart of Sarajevo.

The place where World War I began.

A war-torn Olympic relic is being overtaken by graffiti and nature.

A little sculpture with a large wardrobe.

Christ's blood preserved in a Belgian town.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Deep in the Guatemalan jungle stands an ancient pyramid that once marked the reign of a king.

This staircase full of Mayan hieroglyphics is perhaps the largest single text in the world.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

Giant pagoda houses the car that drove Thích Quảng Đức to his death by self-immolation.