This historic observatory contains the world's oldest refracting lens telescope.

Go inside to really appreciate this 500-year-old technological masterpiece.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

Relics of Australia's convict past, and a modern scene of unimaginable horror.

Christ's blood preserved in a Belgian town.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

Come for the flowers, stay for the bats!

A dilapidated dock tells the story of Titanic's missed arrival.

Hear the tales of New York's most notorious criminals.

Cryptic messages embedded in the New York City sidewalk.

A self-funded cemetery with a long list of inhabitants.

Salute the leader of the proletariat.

Try not to get slimed in Tribeca.

A beautifully eclectic mix of architectural styles.

Ancient snack bar of the Roman Empire re-opened.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Frida Kahlo's childhood home, now a museum of her life and works.

Baroque celebration of the end of the Great Plague of Vienna.

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

The world's largest wooden structure.

5,000 skulls in memorial to those killed by the Khmer Rouge.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

This headstone marks the grave of an 11-year-old boy killed during clashes in the streets over the boycotting of British goods.