This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

A tower marking the spot where Yugoslavia began its resistance against the invading Nazis stands neglected, but not quite forgotten.

Home to a giant switchblade and one of the world's largest collections of pocket knives, this museum is a cut above the rest.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

Reminders of the Battle of Berlin still scar the railway.

Mysterious 500-year-old tapestries depict a unicorn hunt.

This hidden oasis features a stunning view of the Hudson River and the Palisades from a castle-like museum.

A 19th-century shrine covered with prosthetic body parts as votive offerings.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

The encased skull that is widely believed to belong to St. John the Baptist.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

This lesser-known geographic marker was the reference point for all surveys of the continent for 75 years.

The last of Amsterdam's original sea level markers remaining in place.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

The Avenue of Mausolea is a series of grand palatial tombs.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

A hidden gem in the middle of the city's infamous Jewelry Quarter.

New Orleans' famous cemetery, located on the site of a former race track.

The tallest monument in a historic New Orleans cemetery was prompted by romance and dash of pettiness.

America's post-nuclear-attack chambers of Congress.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.