One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

This ancient theater was once the home of fierce gladiatorial battles.

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

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

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

A scattered trail of street art adds a pop of color to the city's stark structures.

This allegedly haunted 16th-century tower house-turned-museum exhibits thousands of spectacular objects.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

The elaborate clockwork contraptions in this Scottish gallery create small worlds of whimsy and horror.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

The fountain marks the area where hundreds of accused witches were burned at the stake.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

360° views of the city plus five floors of optical illusions and hands-on science.

A 30-acre garden inspired by the principles of modern physics.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

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

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

This statue celebrating everyday life in Dublin has a few unsavory nicknames.

A statue in the center of Dublin dedicated to one of their favorite sons of rock & roll.

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