A mysterious plaque to the even more mysterious "Fr. Pat Noise," killed in "suspicious circumstances."

After it was swallowed by a Georgian mansion, this medieval castle remained forgotten for centuries.

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.

This plaque marks a place where one of Hollywood’s most famous dancers got his start.

This public park was the site of the largest civilian disaster of the Civil War.

An 18th-century Catholic church converted into an eccentric temple of music and bacchanalia.

Berkeley Hot Springs presents to you "the only outdoor monument to presidential bathing."

This massive blockhead sculpture hides an entire library.

This ancient theater was once the home of fierce gladiatorial battles.

Five candy-colored villages on the Italian Riviera.

Historic medieval fortified city in southwest France.

This brightly made over hotel hides decades of suicide, serial killers, and mysterious deaths.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

The legendary building that needed ghostly approval before being built.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The largest clock face in the United States is twice the size of Big Ben and infinitely more ad-sponsored.

Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

Once the most painted on object in the world, this short campus fence is well on its way to being so again.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

With 3,000 bikes on display, the world's largest bicycle museum includes some famous rarities.

The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.