Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

Catacombs turned marketplace.

Spitalfields' regal market goat is said to be a monument to the area's migrant population but most are pretty sure it's just a goat.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

Visit the monolithic tomb of America's most famous general.

A portion of the old Pirates stadium over which a defining home run once flew still stands even after the rest of the stadium was torn down.

There aren't too many operational funiculars around, but Pittsburgh has two!

Rumors persist that a bottle of whiskey is sealed within this Demijohn-shaped adornment.

Extraordinary objects lurk in this quintessential regional museum.

These unusual rooms on wheels are holdovers from the 1960s.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

This train station inspired the name of a 1970's rock band and provided the backdrop for their album cover.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

This pre-Revolutionary War grist mill ground corn and flour for soldiers in seven American wars.

Stockholm's deepest subway station is also a stunning ecological wonder.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

This small museum nestled inside a souvenir shop is dedicated to Sweden's most well-known toy.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

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

A temporary art piece to celebrate LGBTQ Pride is now a permanent part of Stockholm's traffic landscape.

What looks like a birch tree smushed between two pieces of glass often confounds commuters.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

This bridge's unique architecture honors nautical heritage and encourages self-awareness.