The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A series of caves, tunnels, and wells filled with fascinating figures and symbols.

This cliff-face port is considered a masterpiece of mining engineering.

The remains of a concrete ship sit on a sandbank between Ballina Quay and Belleek Woods.

At the time of its construction, this hydroelectric power plant was the largest in the world.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

A steam trawler with a whiskey-soaked history driven ashore in 1960 resides rusty but still standing on the shoreline.

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

The remains of this deep, dark mine have left behind a haunting rocky warren of tunnels.

This natural sea arch highlights Ireland's rugged coastal beauty.

Wander among the abandoned ruins of this once-powerful medieval town.

The ruins of a medieval monastery named after a type of tree.

The home of Ireland's last leprechauns is officially protected by the European Union.

A spectacular hidden beach in Ireland has the dark, disturbing nickname of "Murder Hole Beach."

Once the longest bridge in Ireland, this rusting span sits abandoned and overrun by nature.

Obelisks and stone pineapples in the Irish countryside.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

Local legend says the remains of Father Christmas lie within the medieval grounds.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

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

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

Deep in the Negev Desert, the world's tallest solar tower looks like a sight straight out of science fiction.