The longest enclosed pedestrian bridge in the world spans 14 lanes of traffic and six rail tracks, all while lighting up the night sky.

Fifty years after a “blast blasted blubber beyond all believable bounds,” this idyllic natural area commemorates the carnage.

A unique flight of canal locks that owe their form to 19th-century cost-saving measures.

A Victorian marvel of engineering is now a 21st-century tourist attraction.

This 13th century Gothic brick castle is the largest in the world by surface area.

The longest continuous lava tube in Oregon.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

More than 20,000 salt and pepper shakers from across the globe call this museum home.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This collection of ferns from across the globe is the largest assortment in the United States.

A tunnel with windows, so you don't miss out on the impressive views.

The ruins of one of the first railroads in the U.S. lie hidden within a neighborhood cul-de-sac.

This small shop walked so America could run on Dunkin'.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

This seaside Italian village doesn't just look Escher-esque, it actually inspired the mind-bending artist.

What started as a way to address damp basement walls turned into a house filled with intricate hand-carved designs.

A 130-year-old urinal is the oldest of Stockholm and perhaps all of Sweden.

This scenic waterfront swimming pool is the longest salt water pool in North America.

A spiral staircase twists to the top of this unusual Czech lookout tower.

Inside this magnificent 12th-century church is one of the finest carved wagon-roofs in all of England.

This astronomical clock is the second oldest in England.