A 11-foot former president stands on a Kosovo street that also bears his name.

A futuristic, brutalist masterpiece that is also strangely prison-like.

A striking symbol of the Bulgarian capital.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

At this 16th-century monastery in rural Bulgaria, visitors can also spend the night.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

The now-serene site of the largest earthquake ever recorded in North America.

Considered by many to be one of the most dangerous highways in Alaska.

One of the best examples of the modernist movement in Madrid.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Historic medieval fortified city in southwest France.

This massive blockhead sculpture hides an entire library.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

San Francisco's first World's Fair, dedicated to the wonders of California.

The 80-foot tire that looms over Michigan's I-94 was once a Ferris wheel in the New York World Fair.