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

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

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

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.

Rusted cars, trucks, and buses form a fascinating collection of Soviet-era machinery.

A small island dotted with old, historic Finnish buildings.

Villas that once served as playgrounds for the rich now fall away in decay.

A lovingly curated curio shop in which the taxidermy wear newspaper party hats, and peanut shells are spread across every surface.

This endearingly discomfited urinating statue commemorates the sneaky pees had by us all.

A forest park outside Tallinn full of architectural and artistic curiosities.

"There's nothing there," and other lies the KGB told us.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

You can crawl inside this atmospheric 5,000-year-old tomb.

A vintage penny arcade hidden in the back of a fun fair-themed bar.

All that remains of the fishing-vessel-turned-warship is its weathered hull.

The remains of the concrete ship can be seen during low tide.

A rotting air force base is now home to rare birds and scarce plants.

An abandoned 18th century manse looks like something out of an Indiana Jones movie.

Decrepit Victorian public lift is a white-knuckle ride.

A network of concealed passageways lies within a busy London Underground station.

This mysterious underground cave in Shropshire dates back to the 18th or 19th century.

A open air theatre built on a cliff by an eccentric British woman.