1513 Turkish world map, full of European state secrets and snarky commentary.

Home of Howard Hughes' Spruce Goose.

An unusual round church in London with a Templar past.

Where cemeteries are carved into the side of cliffs and infants are buried in the hollows of trees.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

Site of the largest volcanic eruption in the last 25 million years, one which may have nearly wiped out humanity altogether.

A Turkish monastery tucked into a cliff wall.

Soaring over the Niagara Whirlpool since 1916.

A massive, heart-shaped, wind-carved crater in the middle of the Israeli desert.

A unusual sanctuary for abused and exotic animals in South Jersey.

The glowing blue Nymphaeum of Emperor Tiberius.

A very big rock just plopped down in the New England woods.

This quirky roadside attraction dives into the many theories surrounding North America's most infamous hairy cryptid.

Tiny observatory made big contributions to the study of the Earth's motion.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The remnants of an early American attempt at missile defense.

Rusting ships sit in a desert where a sea used to be.

Eighteenth-century home, where Herschel discovered the planet Uranus.

A museum in the childhood house of a medical pioneer.

The headquarters of the Fraternitas Rosae Crucis, complete with Rosicrucian pyramids, all in the Pennsylvania woods.

This structure among the trees was the result of divine inspiration.

An eccentric playboy's astounding natural history collection.

In the middle of downtown Brooklyn lies a 165 year old secret hidden right below the surface (closed to the public indefinitely).

A six-story-tall golden pyramid, surrounded by a moat.