These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

Hidden in plain sight, this creepy sculpture watches from above.

A theatre built to house the rowdy Oxford graduation ceremonies became the stage for a debate about God's existence.

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

The plaques around this 19th-century structure recall some rather strange tales.

This bridge later moonlighted as a local jail.

The first archaeological site discovered by aerial photography.

Famously misunderstood wonder of the ancient world

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

Pop culture has helped to keep this iconic British building from being destroyed.

Eighty million natural history specimens call this gargantuan museum home.

This one has sailed five times as far as Sir Francis Drake's famous ship.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

Hear the quietest sound from across the dome.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Giant, friendly pelicans in Central London, the most unlikely of places.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Rising from the sea like a stone monster.

A little-visited waterfall in an otherworldly landscape.

This elegant arc of a waterfall marks a religious turning point.