An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

Oliver Cromwell once seized the land under this house, which included the ruins of a medieval abbey that the owner used to build his stately home.

Modern sundial uses ancient methods to tell time and date perfectly.

This supermarket offers shoppers a window into the past alongside their groceries.

This Bronze Age tomb is the centerpiece of a clearing within a beautiful Irish forest.

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

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

A once grand hotel now sits eerily abandoned in the Catalan countryside outside Barcelona.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The final resting place of the author who gave us the Little Mermaid, the Ugly Duckling, and many more beloved fairy tales.

The non-native bovine herd was brought in to help conserve these Berlin wetlands.

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

Where once there was a train station bathroom, there is now this German burger joint.

The plague quarantine island home to the alleged "Vampire of Venice."

A new sculpture calls attention to climate change in the centuries-old city it threatens.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

An overgrown and largely forgotten cemetery lies hidden within the outskirts of Amsterdam.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

A Portuguese Jewish cemetery filled with stunning grave monuments that date back to 1614.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.