The ruins of a resort and casino sit on the banks of this blue hole spring that pumps 70,000 gallons of warm, clear water every minute.

Walk down these stairs to get an underwater view of Switzerland's Lake Zug.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

For decades, vendors have sold clothes once worn by American soldiers who stormed Italy in the 1940s.

Pompeii's less famous neighbor is still revealing her secrets.

The oldest volcanology research center in the world.

After 400 years of being closed to the public, this monastery's underground tunnels and secret garden are now a museum.

Come for the 14-foot-long taxidermy alligator. Stay for the mini costumed gators shooting pool.

This medieval city gate is now a blend of the past and the modern world.

San Gennaro, the patron saint of Naples, greets pedestrians between these narrow city streets.

The remains of the left arm of the levitating philosopher-saint are kept in a 13th-century Neapolitan basilica.

This Neapolitan exhibition hall grants weird and wonderful insight into the intricacies of human biology.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

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

The middle finger of modernity.

Hidden in the hills is a mysterious stone structure, known only to a few.

This magical oasis in East Texas is one of the most biodiverse acres in the country.

Rare and classic books by Black authors are the focus at this independent bookstore in a historic Atlanta neighborhood.

One of the world’s largest collections of paper memorabilia chronicles 4,000 years of papermaking.

Constructed during the 7th century this is one of the oldest largely intact Christian churches in England.

The woman who helped save 15th-century France was born in this humble home.

Deep into the lower floors of Pike Place, find a date with fowl fate.

One of the best-preserved medieval streets in Europe.

Supremely flaky treats await at Amadou Ly’s boulangerie and patisserie.