Berlin's old airport.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Clean, cold drinking water flows from a nondescript pipe in a roadside rock face.

During the summer, surfers in Alaska take advantage of this inlet’s unusual water patterns.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

The ruins of a town wiped out by the second-largest earthquake in recorded history.

An Alaska livestock farm devotes itself to harvesting wool from creatures that once ran with mammoths and sabertooth tigers.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

Colorful boxes placed over the dead are left to rot and crumble.

The king of U.S. high points towers over every other peak on the continent.

One man's grief over the national tragedy has manifested in a pod of homemade whales on his front lawn.

Off of the Crawfordville Highway in Florida, nature is taking back this decrepit row of Ford trucks.

St. Augustine's record-setting narrow street was designed to protect against pirates.

The world's largest occupied bat houses hold hundreds of thousands of flying mammals.

This Florida sinkhole hides a rainforest-like micro-environment in its depths.

A mysterious castle built as a monument to lost love.

Where monkeys run wild and the humans are caged.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

Three markers installed over the course of 140 years mark the point where Arkansas, Missouri, and Oklahoma converge.

The final remnant of the Arkansas zinc industry is this historically protected ghost town.