This unassuming bookstore in the heart of Madrid is one of the oldest in Spain.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

Part of the medieval watchtower is displayed in an otherwise ordinary parking garage.

Order cookies baked by cloistered nuns in a 400-year-old monastery.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

The ruins of an ancient stadium that hosted gripping chariot and horse races.

At least according to the Guinness World Records.

A remarkable feat of Victorian engineering across the Firth of Forth.

Built in the 16th century, the tower is now in ruins.

A once extravagant mansion, now reduced to ruin.

A giant pineapple, a symbol of hospitality, and an amazing vacation rental option.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

A hidden medieval crypt where a famous legend says the devil used to teach black magic.

A sublime medieval path adorns the marble floor of one of the most beautiful Gothic cathedrals in France.

A moving memorial to the fallen and missing from WWI trenches.

This memorial museum chronicles the apocalyptic destruction of the First World War.

The site where one of the most famous poems of World War I was composed is preserved to honor the legacy of the work.

In an area where the remnants of WWI are discovered on a regular basis this preserved frontline trench may be the most amazing.

After the construction of a nearby cathedral obstructed the view, the oldest belfry in Belgium was more than doubled in height.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

A whimsical bridge uses saxophones to pay tribute to two great men and the European Union.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Despite centuries of architectural innovation, this French castle is being built like it's the 13th century.