The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The unusual patterns in this rock formation result from two distinct modes of weathering.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A tunnel with windows, so you don't miss out on the impressive views.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

An architect's childhood fantasy treehouse made real.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

These gigantic skeletons tower over visitors and provide insight into the creatures that once ruled over Ireland.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.