Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

The Magical World of George Phar Legler.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

Bizarre Cavern.

A former utopian healing center created by a huckster and built by derelicts.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

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

An enormous park-like oasis, full of famous Chicagoans' graves.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

Delightful disarray of found objects and clutter.

Inside a former cabaret, seven floors of erotic art.

These eerie outliers of the lightning bug family glow a mysterious blue color.

In this century-old literary safehouse, print is alive and well.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

This tangled English forest looks like something right out of a fairytale.

Ruins of the elaborate house where the enigmatic costume designer threw glamorous parties for New York's theatrical elite.

One of the most remarkable caves in all of Iceland was created by a once raging river of lava.

The taxidermied remains of Charles Dickens' pet raven, which helped inspire one of Edgar Allan Poe's most famous poems.

Visible below the waves are memorials to the city's Gold Rush dead.

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

Outsider art meets paleontology at this roadside reptile repository.