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

An 18th-century Spanish watchtower made entirely of seashell and concrete.

A popular European tradition makes its way to the states on one of America's most famous bridges.

Metro station with a claim to rock n' roll fame.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

An overlooked memorial honoring the local Washington residents who died in World War I.

The Corinthian columns that towered over Abraham Lincoln’s inauguration stand proud.

A hotel and restaurant serving as the mecca of kitsch.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

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

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

A marvel of Byzantine engineering under the streets of Istanbul.

The giant pair of sexy legs sticking out the window of this costume store have become its main draw.

2300-year-old Roman road connecting the empire.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Washington's iconic carousel has a nice piece of Civil Rights history.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.