The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

Overshadowed by other, more famous Maltese catacombs, this ancient burial chamber has one of the best examples of a ritual agape table.

These lesser-known Maltese catacombs date back over 1,700 years.

A centuries-old forgotten underworld lies beneath Malta.

This spectacular dome managed to survive after being bombed in World War II, in an event known as the "Miracle of Mosta."

The eclectic seaside sanctuary caters to a rather fowl crowd.

The Jesus tree of Malta bears a striking resemblance to Christ on the cross.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

A hidden tunnel of bones in one of Malta's oldest churches.

This subterranean necropolis holds three floors of antler-dug grave caves.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

A delightful but little-known public observatory and planetarium in Munich.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Hidden beneath the streets of London is a secret subway that only carried mail.

The rocks in this arid basin leave trails of movement behind them.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

The sign at the garden gate reads: "These Plants Can Kill."

A kaleidoscopic warehouse-maze of handmade neon signs.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This faux-seedy Japanese arcade is made up to look like a maze of alleys straight out of a cyberpunk dystopia.