Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

The crumbling remains of a once-grand building.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

Three hundred years of preserved Spanish colonial history in San Antonio.

Locals dubbed it the "Owl Building" because of its bird-like appearance.

Millions of numbers carved in glass represent the tattoos forced upon victims.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

The Boston square dedicated to the dark poet who was born nearby.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

A reproduction of the famous prehistoric cave paintings is hidden underground at the National Archaeological Museum.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

This embalmed man is one of the best preserved mummies from the Canary Islands.

This small museum tucked within a subway station holds pieces from Madrid's past.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

In the fictional world of Kcymaerxthaere, celestial wonders marked a portal to a powerful route of travel at this site in Madrid, Spain.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.