Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

There has been an astronomical clock on this spot since the 14th century.

Pilgrimage site for star-crossed lovers.

Old batteries and frog skeletons reside in this lakeside monument to Alessandro Volta.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

The oldest botanical garden in the world that technically isn't the oldest.

The incorrupt tongue of the patron saint of lost things is venerated in this basilica.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Go inside to really appreciate this 500-year-old technological masterpiece.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Breathtaking and huge 430 year old maps of Italy.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

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

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

Nobles would stage mock naval battles on this large lake at the Royal Palace of Caserta.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.