The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

See some of the world's greatest racing horses at this idyllic thoroughbred breeding facility and garden complex.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

An ancient neolithic tomb that only sees the sun twice a year.

The modern birthplace of Irish freedom.

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

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

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

One of Ireland's most infamous prisons for rebels including men, women and children.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

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

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

World's first "penitentiary," meant to be humane, drove men insane.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Former self-sufficient mental institution now a planned community.

The first piece of public art dedicated to LGBT rights.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

This Upper East Side apartment co-op was designed as a tuberculosis sanitarium.

A plaque immortalizes the spot where the early American spy said his famous last words: "I only regret that I have but one life to lose for my country."

A strangely angled West Village home is the only monument to an explosion that took the lives of three American revolutionaries.

Beautiful mosaics cover the first stations opened on New York City's newest subway line.

The most confusing clock in New York.