These barriers stand as stark reminders of Northern Ireland's troubled past.

These engineering masterpieces are a dominant feature of the Belfast skyline.

Northern Ireland's Brobdingnagian stepping stones.

Cemetery dating back to 1884, known for being the final resting place of the notorious Kray twins.

This tribute to the fictional detective stands at the famous literary character's address.

A museum that chronicles the interesting and often dark history of the London docklands, once one of the major trading ports of the world.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

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

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

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

This ancient causeway can flood daily, leaving Mersea Island as a true island for hours at a time, and cutting its 7,000 residents off from the mainland.

One of the oldest cathedrals in the U.K. houses a priceless early manuscript.

Buried next to Pompeii, this lesser-known Roman villa was the opulent vacation home of Emperor Nero's wife.

Pompeii's less famous neighbor is still revealing her secrets.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

A boat slowly sinking into the Essex mud flats bearing the names of the disappeared that haunt the Thames Estuary.