Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

This triumphal 16th-century arched gateway leads to the oldest street in Palermo.

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

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

In one of the smallest countries in the world stands an original Salvador Dalí sculpture.

Giant topiary dog once played a role in a terrorist bomb plot.

The oldest Roman lighthouse still in use.

An early work of the architect Álvaro Siza Vieira, these swimming pools blend into the beach.

This historic streetcar system has been running since the 19th-century.

This giant sculpture made of trash is a critique of society's wastefulness.

The stunning interior of this Gothic church is covered in ornate gold details.

Elaborate tile work in this railway station tells the story of Portugal.

A hidden three-foot-wide house separates these two regal churches.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

The burial place of 14 of the executed leaders of the Easter Rising.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.

After it was swallowed by a Georgian mansion, this medieval castle remained forgotten for centuries.

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

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

This colorful and fiery mural depicts the Irish folk story of the beloved hero Cuchulain.

The block of aged dairy is probably still edible after 2,300 years in a peat bog.

The house where the writer spent his formative years.

The 19th-century pharmacy (now a used bookstore) was featured in James Joyce’s "Ulysses," and has changed very little to this day.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.