The site of Austria's biggest concentration camp now honors its victims.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

Go inside to really appreciate this 500-year-old technological masterpiece.

The celebrated eyesore created by starry-eyed sweethearts.

A massive Montreal stadium that has seen nothing but trouble since its inception.

City law dictates that this mountaintop cathedral containing the heart of a saint is to remain the tallest building in town.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

This inexpensive lodging house was once a prison notorious for its inhumane practices.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Perhaps the most scandalous statue of America's first president.

Home to items never before seen by the public.

South Dakota's oldest operating brewery is housed inside a historic firehouse.

Every president in history is immortalized in bronze in downtown Rapid City.

A cemetery housing wild west legends in South Dakota.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Collection of skeletal systems from the "world's leading supplier of osteological specimens."

World's largest precision optical instrument used to detect Einstein's elusive gravity waves.