The Avenue of Mausolea is a series of grand palatial tombs.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

This church carved into the rocks is full of enchanting stone statues.

The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

Drink and dine in a coral cave that's at least 120,000 years old.

This eerily opulent residential museum is home to a haunting local legend.

This 16th-century church now has a heavenly second life as a cultural hub of Pátzcuaro.

The interior of this Serbian royal family's mausoleum is covered with exquisite mosaics.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

This $62 million dollar temple was erected to house one little dental fragment of religious history.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Its frescoes depict the likeness of Marshal Tito, Karl Marx, and Friedrich Engels burning in hell.

Black cat statues guard this temple-like Egyptian revival factory.

This once-derelict building is now one of the most beautiful bookstores in the world.

This gorgeous Peranakan mansion’s family heritage includes a century-old baby gate, which was also used to keep out irresponsible husbands.

In Twickenham sits a small whitewashed castle that inspired Mary Shelley's 'Frankenstein.'

Hundreds of Buddhas in a re-discovered Indonesian temple.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

This dazzling Art Nouveau mansion is now home to the Modern Art Gallery Subotica.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

Dine on Hungarian-Jewish dishes at this multigenerational, family-run institution.