Overlooking the Colorado Convention Center is this giant sculpture made from thousands of triangles.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

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

This historic hotel invented the chocolate brownie.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The Great Fire of London and the regulation of one-way streets both started in this alley.

The commemorative stone column conceals a secret laboratory.

This one has sailed five times as far as Sir Francis Drake's famous ship.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

Thomas Edison's home and final resting place also boasts an impressive garage, where some of the earliest electric cars are on display.

A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

Take a dip in the world's largest mineral hot springs pool.

A wooden theatre that remains the heart of a charming Victorian-era New Jersey enclave.

A reservoir of vintage pinball machines and arcade games for the nostalgic and thrill seeking.

A section of the long chain that blocked enemy ships from entering Constantinople.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

1513 Turkish world map, full of European state secrets and snarky commentary.