Unrepaired walls from a 1920 anarchist bomb attack.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Numerous stone coffins from different centuries, lined up in a sixth century basilica.

What is it about mushrooms that makes people wish they lived inside of them?

What is the Thing?

The largest copper mine in Arizona, this enormous open pit emerges from the hills like an alien landscape.

The world's first interactive human body museum also serves as a chair for a giant orange man.

Stand at the center of this lakefront sundial, and you'll become part of the timepiece.

Dispersed across 45-acres, 39 structures house a massive collection celebrating American Folk Art.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

One of the world's few mounted blue whales, its jaws are hinged open allowing visitors to descend into a lounge.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

The only boathouse Frank Lloyd Wright ever designed was also the only unbuilt structure in his famous Wasmuth Portfolio, until 2007.

This contemplative sculpture made out of old machine parts is meant to be the first in a series of sculptures around the world.

Hans Christian Andersen for the postmodern world.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

The shiny silver little brother to Copenhagen's Little Mermaid statue.

Explore a misty river canyon from a metal bridge system.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

This groundbreaking 16th-century map is known as "America's birth certificate."

An Industrial Revolution-era public work that purified water using nothing but sand.

This memorial honors thousands of enslaved Africans and their descendants who died in colonial New York.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

The National Park Service’s best-kept secret with views that rival any in D.C.