This historic stone bridge has an entire neighborhood clinging to its sides.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

This historic hotel invented the chocolate brownie.

All of Chicago's wood-paved streets are long gone but two alleys remain.

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

New York City's only preserved family home from the 19th century.

Lie in a hammock where George Washington stood.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

A series of modernist treehouse hotel rooms grace the outskirts of an Arctic forest.

A hollow cement depiction of time's inexorable effect on the human body.

A very classy 1920s-era bar right in Grand Central Station.

The oldest landmark of Toronto is a testament to shifting sands.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

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

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Rent out a glass igloo to watch the Northern Lights like you live in the future.

This little museum is built on a theater that was once a wildly elaborate speakeasy.

The most visited, and possibly most controversial, museum in Germany.

New York City's smallest piece of private property.

A monument to the art of slicing people open.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.