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

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

The Vatican's secret porn-festooned bathroom was painted in erotic murals by one of the greatest artists of the Renaissance.

Breathtaking and huge 430 year old maps of Italy.

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

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

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

For one day every month Barcelona's Estació de França transforms into a market for model trains.

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

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

One of Europe's largest supercomputers is housed inside of a disused chapel.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

A temple to modernity, tucked away amid Barcelona's more well known museums.

Turntable anonymously received orphans, alms, and groceries.

A stately palace has been converted into the world's largest cannabis museum.

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

Week-long block party becomes a competition for the best decorated street.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Slovenia's first mosque is a striking mix of Islamic and modernist architecture.

A relic from the Industrial Revolution got a second life as a contemporary performing arts space.

A crumbling World War I fort that is reached through a series of concrete tunnels.

A beautiful drive through the foot of the Alps traces the path of 15th-century Turkish raids.