A remarkable feat of Victorian engineering across the Firth of Forth.

This mundane post marks the old location of the city's main postal hub.

The Guinness Record holder for largest hedge in the world is a verdant Scottish bulwark.

A six-ton wedding present for the King of the Scots.

This obscure walkway links Edinburgh’s Old Town with one of the city's prime vantage points.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

The castle still holds traces of the abandoned Roman fort it was built atop.

The longest and tallest aqueduct in Britain can actually be sailed across.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

This memorial was created by an Irish nurse who lived in New York City during 9/11.

Behemoth, cannon-like telescope operated by generations of Irish earls.

The block of aged dairy is probably still edible after 2,300 years in a peat bog.

These imposing walls and towers look more like the ruins of a fortress than a monastery.

This single room has survived the centuries with almost no deterioration.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

The enchanting archway is the only surviving portal into Dublin’s lost medieval wall.

The ancient tomb acts as a calendar that keeps perfect time.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

This stucco building in North Africa was the first American-owned property on foreign soil.

The city walls of Salé lead to the ruins of this seaside "bastion of tears."