The site of the deadly Triangle Shirtwaist Factory Fire.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

One of only two commuter aerial tramways in the United States.

An expansive and intricately restored mansion remains from over a century ago--and so do its ghosts.

One of the last free public hot springs is decorated with hippie art.

The unbelievably opulent home built for an infamous newspaperman.

A multimedia experience that chronicles the atrocities of racism.

Quite simply the largest tree in the world (by volume).

San Francisco's newly reopened hands-on science museum.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A monument commemorating the role of Alaska's native Tlingit guides in the Klondike Gold Rush.

A tiny wilderness cemetery commemorates the deadliest episode of the Klondike Gold Rush.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.

A classic gold rush hotel can be expected to pick up some ghosts along the way, and the Golden North is no exception.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

Scenic mount trashmore, Virginia Beach's most curious waterfront still has a couple of secrets.

At 207 feet, one of the world's longest continuous escalators.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Once the site of the Hawaiian monarchy, this building was originally designed as a palace.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.