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 former fisherman's hut deemed too small for habitation is now a delightful tourist draw.

Picturesque ruins once held off mighty armies.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

The highest peak in Wales is said to be the final resting place of a giant killed by King Arthur.

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

A hermit's tiny cell built into the cliffside that saved him in South Pembrokeshire.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

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

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A medieval church built up to defend its village.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

Something's watching you.

Conspiracy theories and occult legends surround this mysterious natural rock formation.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.