Once called "the biggest room in the world," this Victorian-era hall is so large that it contains a smaller 1970s heptagonal theatre.

Underground hospital complex constructed by slave laborers during the German occupation of the Channel Islands.

This natural crater along the coast of Jersey may take its name from the devil statues who have watched over it.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

Single runway interrupted by a busy road that cuts across its middle.

The San Marino-Rimini railroad was short-lived but this tunnel once provided shelter for hundreds of refugees during World War II.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

Some of the smallest works of art in existence.

The world's largest collection of fire-fighting items dating back almost 350 years.

In one of the world's smallest countries, a royal's personal winery is open to the public.

One hundred years ago this small house in downtown Zürich became the birthplace of the Dada movement.

One of a series of no-purpose kinetic artworks by Swiss sculptor Jean Tinguely.

The World Wide Web was created in this nondescript corridor at CERN.

A trove of ridiculously valuable prints and manuscripts under one roof.

An unassuming churchyard is the resting place of a pioneering surveyor and reluctant namesake of a mountain.

A gigantic collection of teeny, tiny books.

A unique museum dedicated to culture and artistry of carpet weaving.

This mysterious but iconic tapered tower appears in many Azeri fairytales and legends.

The building's fluid, wavelike walls are a true feat of architectural ingenuity.

A shrine of fire worship built on top of a natural flame.

This hydraulic power system in London was, at one time, seen as a rival to electricity and the last of its kind to shut down.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

An old slaughterhouse now holds the largest collection of pig artifacts.