A former major munitions plant that has been converted into a sprawling art space.

America's first federal monument.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

Second largest wastewater treatment plant in the country.

A monument celebrating the idea of reaching inaccessible places.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

An idyllic swimming pool tells the tale of Hemingway's trouble with women.

The highway's southernmost spot is a beloved local attraction.

A historic landmark and museum filled with curious objects representing the history of Key West.

The magic's in the hole!

The seamy, underground secrets of Portland's criminal past.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

An emporium for the weird, creepy, rare, and just plain gross.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

The 25th President's marble casket can be visited in this classical Ohio tomb.

Mausoleums, astronomy, and animatronic dinosaurs at this memorial to an assassinated American president.

The romance of early commercial flight still fills this Art Deco destination.

Two thousand artifacts from around the world collected by one woman who loved to travel.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

This small glass cube is a peaceful out-of-the-way sanctuary at the busy airport.

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

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."