This controversial Irish show cave is home to a massive formation known as the Great Stalactite.

The remains of a majestic house that was once stood in the crosshairs of the Irish Republican Army.

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

An Irish peat mine has become a stunning sculpture park.

Once an early Christian burial site, it's believed the location was home to around 200 gravestones.

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

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."

An unassuming historical marker for an iron age fort leads you to an oddly adorned cemetery for unbaptized children.

The chaotic studio of one of the 20th century's most important artists has been preserved down to the dust.

This pub built its reputation pouring post-shift pints for employees of the cemetery with which it shares a wall.

A moody and picturesque riverside ruin overgrown with vegetation.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

One of only two commuter aerial tramways in the United States.

A little lighthouse in New York City, surrounded by mysterious stories of insanity-driven construction.

The best B-movies filmed on a shoestring budget were born here.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

The most unloved grain elevator in Brooklyn was a “Magnificent Mistake.”

Compensation for the destruction of a historic shipyard.

Where infamous mobster and leader of Murder Inc. Albert Anastasia made his home.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

A riverfront park that both remediated and preserved its industrial past.

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

Deep under Manhattan is the largest construction project in city history. So far, the project has taken the lives of 23 workers, or "a man a mile."

During the 19th century, you could pay for violence off a prix fixe menu on this Manhattan street.