A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

Once the foundation for a mansion, these ruins now offer amazing panoramic coastal views.

This Costa Rican topiary park is a surreal garden of unearthly delights.

The world's largest wooden structure.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

A layered tribute to the work of mosaicist Isaiah Zagar.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The national park was once a plantation estate.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

When it opened during the final years of the embargo, all the drinks and cigars were free.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

The United States Capitol's former columns still stand.

This influential Renaissance-era library was once the haunt of kings and monks.

During an annual Catholic feast in this tiny Spanish village, men dressed as devils leap over rows of babies to cleanse them of sin.

This 47-story "M" needed 20 years to be completed

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

A micro-communist utopia in Spain with no police, no mortgages and full employment.

An eerie collection of the surviving structures from a past celebration of the future.

A 16th-century Andalusian palace.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

This quaint Spanish village agreed to be painted blue as a marketing stunt but found that they preferred it that way.

The chefs at El Diablo use heat generated by an active volcano to cook the food.

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

A lush indoor jungle fills this bustling Madrid transportation hub.