This massive mushroom has spent centuries eating its way across a huge swath of Oregon.

This little-known collection holds everything from "Dracula" notes, to the manuscript of "Ulysses," to the forged works of Shakespeare.

This evocatively named natural crevasse was created by a torrent of water that smashed right through a granite deposit.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.

An unrealized dream to wirelessly electrify the entire Earth.

The only free-standing, vertical sundial in the US was keeping standard time before it was even invented.

Ancient church constructed with a special wood that preserves prints from the past.

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

Arlington Cemetery exhibit dedicated to death and grieving.

Civil War dumping ground for the bodies of terrorized Union sympathizers.

Civil War-era Fort designed to withstand invasion and attack, with tricky traps called "murder holes."

Civil War Fort on an island in the Boston Harbor.

The state's oldest continuously operating museum houses more than 5,000 Civil War artifacts.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Suburban observatory was personal lab of the father of modern astrophysics.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

In upstate New York, gorgeous waterfalls and a watermill are slowly being reclaimed by nature.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.