One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Elevated freight railway turned wildly successful urban park.

Avoid gangster interaction while window-shopping.

The most confusing clock in New York.

Cryptic messages embedded in the New York City sidewalk.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

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

The first American department store, and home to the largest operating musical instrument in the world.

Home to items never before seen by the public.

One of Savannah's oldest and most haunted cemeteries, featuring graves desecrated by Sherman's Union Army.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

Largest lake in Great Britain measured by surface area.

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

A little sculpture with a large wardrobe.

Christ's blood preserved in a Belgian town.

Romania's triumphal arch looks out over Bucharest.

Ancient serpentine sacrifice holder that has stood the test of time.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.

Fortified homes of highland warriors that are still in use today.

A gleaming white and undulating tower marks the border between Georgia and Turkey.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

Unusual building appears to be haphazardly built from randomly piled bricks.