This enormous censer uses a pulley system installed over 400 years ago.

Once a palace for the Archbishop of York, these 15th-century ruins now serve as a haunt for history buffs.

This network of narrow, medieval passages has the most delightful name.

This memorial to World War II's fallen airmen shows us the movements of the stars that once guided them.

Once the largest factory complex in all of Europe, this converted shopping center celebrates its industrial past in a big way.

English Protestants once criticized this enormous private chapel for being too ornate.

The unusual sculptures are believed to be powerful political symbols.

A crushed gate and giant bronze head serve as a reminder of Greece's fight for freedom.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

A little-known park with unusual, half-ruined structures and a mystical energy.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

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

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.

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

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

Saint Joseph was said to heal the deaf and blind, but it was a much smaller miracle that got him canonized.

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

A section of the long chain that blocked enemy ships from entering Constantinople.

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

The English Civil War began right here in 1642.

The collapse of the brand-new dam caused one of the worst floods in British history.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

In England, an 18th-century water-powered workshop still stands.