The Guardian of Tallinn.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

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

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

A Bibliophile's Dream.

The world's largest talking cow would like to tell you about the benefits of 100% Wisconsin dairy products, if only she still could.

Elaborate drama imparts an appreciation for 19th century hardships.

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

South Dakota's oldest operating brewery is housed inside a historic firehouse.

Every president in history is immortalized in bronze in downtown Rapid City.

A six-ton, 12-foot-tall concrete prairie dog is touted as the largest in the world.

A fitting attraction for the corn capital of the world.

A cemetery housing wild west legends in South Dakota.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Long before guestbooks and hotels, frontier travelers signed their names on this rock face.

The first declared National Monument in the United States.

The final resting place of American icon Buffalo Bill, and a museum that aids in telling his tale.

The first car-centric shopping plaza in the U.S. brought a little bit of Spain to downtown Kansas City.