One of the largest underground systems runs under Canada's largest urban center.

One of Canada's most incredible rare book collections holds hundreds of thousands of gorgeous tomes that the general public can touch.

This historic national park is covered in the stunning ruins of red rock pueblos.

Ancient pueblos built into the base of a natural canyon wall.

A fitting attraction for the corn capital of the world.

A mysterious castle built as a monument to lost love.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

A favorite of Amelia Earhart, ranking among those rare bridges that can be crossed without changing sides of the river.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

A 70,000-square-foot institution dedicated to a very literal, creationist perspective on the Book of Genesis.

On the right bank of the Grand River a plaque remembers an imaginary painter who once awaited his youth.

An angular maze of concrete in Grand Rapids acts both as public art and as a staircase for fish traveling upstream.

The only surviving prototype for Buckminster Fuller's house of the future.

A monument to the 17,000 Chinese who worked and died to build Canada's Pacific Railway.

This massive, ancient stone was disassembled and then put back together again.

One of the foremost Sherlock Holmes collections is hidden away at a Toronto library.

The oldest landmark of Toronto is a testament to shifting sands.

Willy Wonka would love this weird half-a-home.

With well over 130 falls and cascades to brag about, Hamilton, Ontario has earned its stripes as the waterfall capital of the world.

The tunnel under the Capitol Building where Congress takes out its trash.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.