The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The site of the climactic scene from the classic horror film is now a historic landmark.

Knoxville’s architectural icon was the symbol of the 1982 World’s Fair, even catching the googly eye of Bart Simpson.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

This stunning concert hall has become a symbol of Iceland's national recovery.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

The design of this beautifully crafted building was inspired by Norwegian glaciers.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Op-art architecture designed for happiness.

A spherical "micro-nation" in the heart of Vienna.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This automated sculpture of two men peeing will spell out text messages with their micturition.

The first museum in the world devoted to sexual gadgetry.

Macabre astrological automaton clock dating to the late 1400s.

A church of bones, decorated with 40,000 human skeletons.