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

An abandoned canal route lies hidden under the streets of Manchester.

One of the highest Roman forts in Britain is set amid dramatic scenery on a notoriously difficult road.

The ruins of Scottish sea salt production.

The biologist's fossilized headstone was meant to reflect his love of nature. Its, ahem, unusual shape is probably just a coincidence.

An octagonal folly tower overlooking the sea.

These abandoned coal mine towers near Sherwood Forest might soon boast the U.K.’s longest zip-line.

In the right conditions a wall of water up to five feet tall flows upstream against the current on the River Trent.

The world's first purpose-built motor racetrack was destroyed by the outbreak of two world wars.

The rust covering this old mine's abandoned buildings matches the red pigment it once produced.

This early Norman castle was the first historical monument protected by an act of Parliament.

The longest stone bridge in England has an impressive history that dates back over 700 years.

The sign announces the Scottish village's cosmic connections, as it's twinned with Glenelg, Mars.

A bizarre stone beast lurks on the beach of a popular tourist island.

Derelict chemical plant on the North Sea is a beautiful industrial ruin.

Though much of the castle was robbed of its stones, the underlying earthworks are among the best-preserved in England.

Overlooking the burial ground is a tower designed to prevent thieves from snatching the recently deceased.

This aging storage facility is the world's largest brick warehouse.

Arthur, Merlin, and Guinevere are among the largest and oldest satellite dishes on the planet.

These ruins of Francis Bacon's once-magnificent manor are hidden in the English countryside.

An abandoned World War II tank left to rust in the downland.

This crumbling 14th century chapel became so unstable the roofing apparently collapsed during a wedding ceremony, narrowly missing the curate's head.

A motley, fantastical agglomeration of unlikely houseboats along the Shoreham-by-Sea riverbank.

It might not be as impossible to reach as its name would imply, but just about.