Where condemned pirates met their grisly end at the gallows on the River Thames.

A relic of Victorian grandeur hides beneath a busy South London road.

This coffee shop lies hidden beneath a historic church.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Created hundreds of years ago, the magical follies and landscapes at this park were almost lost to time before being restored.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.

The largest of London's subterranean rivers and once a mad, bad center of London life.

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

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

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

The anatomical-pathological collection of a man who changed surgery.

Remnants of a Victorian garden feature sitting in public woodland.

An unusual round church in London with a Templar past.

Rebuilt remains of a temple to Roman god Mithras.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

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

The world's largest collection of witchcraft regalia.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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