This small Estonian hill is covered in hand-made twig crosses that are said to bring good luck.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

The gutted remains of this Estonian mansion are a monument to a tragic love.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

A subterranean house of worship carved right out of the bedrock.

An eccentric playboy's astounding natural history collection.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

Two New York rooftops are home to the largest rooftop soil farms in the world.

This South Carolina water tower is an icon of the city of Walterboro, but it also once served as the county jail.

This bare tree might not have leaves but it is constantly clothed in festive decorations left by mysterious local benefactors.

The only free-standing, vertical sundial in the US was keeping standard time before it was even invented.

According to local lore, this narrow passageway through two large rocks was accidentally created by the devil himself.

This natural wonderland is a unique chance to explore a Carolina bay, a mysterious geological formation of unknown origin.

The world's largest fire hydrant is supposedly tornado-proof.

This titanic steel chain linking two buildings was installed without permission but instantly beloved.

This recently rediscovered Civil War-era submarine was the first to ever sink an enemy ship.

A quirky Poe-themed joint on an island keen to celebrate its overlooked connection to the famous writer.

Granite outcropping that the state's tourism bureau doesn't promote because of its delicate ecosystem.

This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

An unfinished rail tunnel that has since been used to house cheese and bats.

One of the oldest living oak trees in the Southeast.

This airfield is home to a number of retired vintage planes in various states of disrepair.

A sign marks the plane crash that caused two nuclear bombs to fall in North Carolina.

Down the road from where the Wright brothers lifted off is another flight tribute practically hidden from sight in the woods.