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

One of Australia's largest secondhand bookstores.

Built over an abandoned train yard, this hidden gem is full of winding paths and offers gorgeous views of Sydney Harbour.

These ornate arches show how the course of the River Thames has changed.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

London's old-school healing garden.

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

A mysterious artist-run cabinet of curiosities and library.

London's smallest police station is barely the size of a phone booth.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

Catacombs turned marketplace.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

One of the few remaining examples of 19th-century London’s attempt to clean up its reputation.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

This luxury shopping lane has been protected by its own tiny police force for over a century.

London's largest outsider art museum.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.