This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

A peculiar family mausoleum built by a German nobleman captivated by the occult.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Only 68 people per day are allowed to visit this New Zealand bird-watcher’s paradise.

The haunting peak of an old church is all that remains of a drowned Brazilian city.

Designed to allow funerals to proceed over the River Dulnain.

Water of undetermined depth has attracted rare fish and cult leaders alike.

Take a ride back in time with a steam locomotive trip through Eritrea’s mountainous countryside.

This simple rock stands as a memorial of the major student protests of 1968.

Thousands of graves lurk below the surface of this park.

This log house sits in the remote Canadian wilderness, and holds a mysterious tale of the trapper who built it.

A vast Communist-era exhibition space in the Bulgarian capital.

This enchanting hill is home to fairy lore and a sinister local mystery.

The tomb of one of the greatest travelers in history.

This massive underground salt mine now holds a sci-fi theme park in its depths.

The cheese slicer may be a Norwegian invention, but the biggest ones in the world are found in Sweden.

Once a safe haven for locals engaged in blood feuds, this 400-year-old fortified tower is now a museum showing what life was like for those lying in wait within its walls.

The cell which saved the life of Ludger Sylbaris, "the man who lived through Doomsday."

After 400 years of being closed to the public, this monastery's underground tunnels and secret garden are now a museum.

A group of college students hauled a desk up a mountain more than 40 years ago. The notebooks inside have become a makeshift time capsule.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

This lovely little burbling creek is actually a deadly waterway that has dragged down everyone who ever set foot in it.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.