A hugely vast Irish landscape of barren rock that stretches for miles.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

The most northern place on the mainland of Great Britain.

A sea cave with a waterfall and Viking past

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

Amsterdam's former hotspot for public executions and dissections.

Museum preserving torture methods from the past.

An ornate private entrance to the Vienna subway built specifically for the emperor.

This grand manse has been transformed into a museum devoted to one of the founders of Fantastic Realism.

The first modernist church in Europe.

The housing complex served as an anti-fascist fortress during the Austrian Civil War.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Legends surround an ancient tree trunk riddled with nails for good luck.

Op-art architecture designed for happiness.

Baroque celebration of the end of the Great Plague of Vienna.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Deep in a Polish forest, this collection of Iron Age megaliths still holds onto many of its ancient secrets.