San Francisco's newly reopened hands-on science museum.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The underground sanctuary of a mysterious ancient cult.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

2300-year-old Roman road connecting the empire.

The yawning maw of this pagan visage is said to bite off the hands of liars.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

All that remains of a Japanese fishing vessel that ran aground in 1982.

This small monument marks the divide between the Atlantic and Indian Oceans at the southernmost tip of Africa.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

At 72 feet below sea level, it's the lowest commercial airport in the world.

Breathtaking and huge 430 year old maps of Italy.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

This historic system is the zero level benchmark for measuring the depths and altitudes of the Baltic.

This Russian museum stresses the importance of keeping clean and even holds one of Pavlov's dogs.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

A replica of the straw hut where Vladimir Lenin lived in hiding, disguised as a hay farmer, in 1917.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.