A vibrant street away from the typical tourist track, lined with colorful, mosaic-covered houses.

A gateway to a mysterious network of underground tunnels.

This historic, palatial theater is now one of the world’s most beautiful bookstores.

This small museum tucked within a subway station holds pieces from Madrid's past.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

This tiny, tucked-away eatery reflects the history of Mexico's Lebanese immigrants.

The ruins of an ancient temple to the Aztec wind god discovered in the middle of a metro station.

This one-window stand has been home to a giant vat of slowly simmering meats and an array of unique tacos for almost 50 years.

CDMX's home for the world's culinary delights.

By night, this auto repair shop turns into a taquería serving up some of the city's finest al pastor tacos.

Murals made with millions of colorful stones adorn the abandoned building.

At a museum of everyday objects, it is the act of collecting that is really on display.

A disquieting Aztec sculpture displays hundreds of stone skulls representing the victims of human sacrifice.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

Spend your honeymoon where the Devil had his wedding.

An underground nightclub helped spark a "Singing Revolution."

The oldest continuously operating pharmacy in Europe.

"There's nothing there," and other lies the KGB told us.

A unique seaside cave where Aleister Crowley faked his own death.

This unique architectural wonder is also tied to one of the 20th-century's most renowned writers.

Ring the bell to enter a bar that looks equal parts museum and old curiosity shop.

The best place in the world to buy tinned fish.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.