The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

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

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

Hear the quietest sound from across the dome.

An unusual round church in London with a Templar past.

Eighty million natural history specimens call this gargantuan museum home.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A tiny island off the coast of Dublin was once a pilgrimage site for the sick and the suffering.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

The Grand Lodge of Ireland is one of the oldest in the world, full of fantastical, elaborately themed rooms.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

A series of eerie metal stick figures are spread out over four square miles on the bed of a huge salt lake in the Australian Outback.

Nine limestone rock stacks on Australia's "Shipwreck Coast."

Come for the flowers, stay for the bats!