Some of England's last cave dwellers lived and worked within this huge cave.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

This curious, round temple is the oldest still-standing marble building in Rome.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

Some say this medieval church is where the poet Dante married his wife and also met the love of his life.

This amazingly preserved Doric temple was abandoned before it was ever completed.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

The "Great Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

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

This unassuming alcove in London’s famous Tower Bridge once served to capture, store, and display dead bodies from the River Thames.

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

Overlooking the seaside town of Margate stands a tribute to an artist's lover.

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

This Native American settlement dates back to the Pueblo II period.

Semaphore saints, a golden dragon's head, and a stone carved with religious warnings all call this cathedral home.

More than 25 fully functional scale replicas of famous lighthouses dot the shores of Lake Havasu.

A tribute to the statues of Easter Island along Route 66.

This archaeological site built into a tuff outcrop is filled with rock dwellings, the ruins of a medieval castle, and a necropolis.

This network of roads is one of the most unique Etruscan creations ever discovered.