On the wall of this medieval walkway, a symbol of the Spanish Inquisition.

A once-secret library of Freemason history in Catalonia.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

The world's largest wooden structure.

The final resting place of the great navigator, or maybe his brother.

Hidden behind a wall, Spanish nuns distribute their signature sweets on a revolving tray.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

Drink the 'Blood of Christ' in this Roman Catholic fever dream.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

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

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

The remains of this deep, dark mine have left behind a haunting rocky warren of tunnels.

A particularly disconcerting tribute to Irish martyrs.

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

Some of the saint's blood and bones are said to reside in Dublin.

This pub built its reputation pouring post-shift pints for employees of the cemetery with which it shares a wall.