The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A modernist landscape of water and sci-fi concrete.

An enormous pink granite batholith, long attributed with spiritual powers by the Tonkawa Indians.

Three hundred years of preserved Spanish colonial history in San Antonio.

Giant heads occasionally litter the industrial Houston neighborhood where sculptor David Adickes has his studio.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Largest necropolis in the Mediterranean.

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

Breathtaking and huge 430 year old maps of Italy.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The final resting place of the poets Shelley and Keats.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

A Nesting Doll of Churches.

A sculpture serving as an homage to Pope John Paul II.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The underground sanctuary of a mysterious ancient cult.

Baroque celebration of the end of the Great Plague of Vienna.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.