A maze of underground tunnels beneath one of the most beautiful forts in Serbia.

Historical figures from New York City's Catholic community reside in Midtown.

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

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

Overshadowed by other, more famous Maltese catacombs, this ancient burial chamber has one of the best examples of a ritual agape table.

A neo-Gothic temple in central Mexico featuring a labyrinthine network of crypts.

A hidden gem in the middle of the city's infamous Jewelry Quarter.

Ancient catacombs form the foundation for this Rococo orgy of a church.

These lesser-known Maltese catacombs date back over 1,700 years.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

A burial vault located under Tiber Island in the middle of the Italian capital.

These 17th-century mummies are no longer naturally preserved, but remain on display today.

Thousands of well-dressed mummies below a monastery.

Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

The crumbling remains of the first Black-owned and operated hospital in Kansas City.

Four, 18-foot-tall badminton shuttlecocks lie scattered about the lawn of a Kansas City museum.

Undone by Prohibition, this abandoned brewery-turned-flour mill is now ready for its third act.

The famous greeting card maker owns a collection of paintings by the famed surrealist.

A piece of John the Baptist in the American heartland.

The world's largest collection of fine-scale miniatures and one the nation's largest collections of antique toys.

Community bookshelf of 25-foot-tall book spines.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.