These morbid carvings remind churchgoers of the inevitability of death.

A Roman spa buried deep beneath the City of London.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

This small collection of rare books was uniquely locked up for safe keeping.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

A glorious pub known for a spiteful printing feud and its famous typeface lost—then found—at the bottom of the Thames.

A famous burial ground with a history both grim and literary.

A Victorian park cemetery, standing on the site of what was once the Great North Wood.

Charles Babbage's proto-computer, painstakingly brought to life.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

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

A historic arboretum and non-conformist, non-denominational park cemetery.

Artists and musicians now rule over this former rail station.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

Scattered throughout London are ancient remnants of the city's former bounding wall.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

The remains of Crystal Palace Great Exhibition of 1851.

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

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