A wonderland of caves in eastern Iowa.

Hidden in the grounds of the Fort Dodge Museum is a "real" and terrifying petrified giant.

The remains of a bustling turn-of-the-century park built to showcase the wonders of electricity.

A mysteriously dark cemetery monument fuels stories and legends galore.

The world's largest otter started his life as a high school shop project.

It's believed the soldier was 109 years old when he passed away.

Minnesota's highest point is a scenic vista marked by a plaque and armies of mosquitoes.

This posh mansion began as a family's estate and ended as the site of a murder ripped from the pages of a pulp novel.

A mapping error in the 19th century made loggers think this section of the forest was underwater.

A stone marker commemorating the first time sound was transmitted over wires.

This supermarket offers shoppers a window into the past alongside their groceries.

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

A spring purported to have healing properties lies just outside Scotland's capital.

This extinct volcano rises above Edinburgh and is special for its panoramic views over the city.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

This series of Scottish caves has no clear purpose other than baffling historians.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

This punny mirror of another Wisconsin attraction is exactly what it sounds like.

The hidden ruins of an old hydroelectric plant reclaimed by nature.

The ruins of a 2,000-year-old Roman fishing village perched on one of the best beaches in Spain.

Red, white, and blue painted steps along with a Union Jack celebrate the outcome of Gibraltar's 1967 referendum.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

This simple convenience store sits on the location where the Ouija board was named—and has a plaque to prove it.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.