The second largest in the world, this massive underground void has its own subway.

Ancient rock-hewn town that witnessed key events of Georgian history.

Luxury hotel turned into a refugee camp, then turned back into a luxury hotel.

Florida castle built with aluminum printing plates.

Remarkably realistic Florida shoal bass "swim" inside this large globoid sculpture.

This popular tourist cave was ignored for almost 200 years before being mined into an attraction.

A monument to Cuffy, a rebellious enslaved person who became a national hero in Guyana.

The end appears to be nigh for the world's fourth-longest floating bridge.

Though dynamited and defaced, the statue still stands outside the law courts in Georgetown, Guyana.

Georgetown’s most impressive building is also one of the tallest wooden churches in the world.

The largest market in Guyana, designed and built by the Edge Moor Iron Company of Delaware.

The world's widest single drop waterfall, and the two men who legend says went over its edge in a boat.

A bright little alley in La Boca is a part of tango history.

Buenos Aires' city of the dead contains some very famous remains, including Eva Perón.

A series of waterfalls so massive they straddle the border of Argentina and Brazil.

The design of the Palacio Salvo has been described as "a lighthouse on top of a building."

Eduardo Kobra’s breathtaking 32,300-square-foot graffiti wall took over Rio’s Olympic Boulevard.

A 125-meter long "tribute to the Brazilian people."

This massive Brazilian church is built like an angular, technicolor pyramid left by Mayans from the future.

The final resting place of soldiers' loyal canine companions.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

This London marker celebrates the spot where the world-famous English band was founded.

An architectural oddity hides in plain sight on this iconic London bridge.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.