Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

A dreamlike medieval church dug into the tuff rock, with unusual carvings and possible traces of the Templar knights.

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

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Deep in the countryside lie the remains of one of the grandest Roman dwellings in Britain.

Hundreds of hidden passageways weave through the old quarters of Lyon.

This unusual rock formation looks like an apple that has been neatly sliced in half.

A monument to the thrice mayor of London who according to lore made his fortune by selling his rat-chasing cat.

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

This unusual geoglyph was built as a warning so low-flying aircraft wouldn't scare the zoo animals.

A Japanese cat island also populated by the descendants of a band of banished samurai.

This feline raises a friendly paw at drivers barreling toward the freeway.

These lush botanical gardens employ the most purrfect pest control force.

An abandoned Cold War missile radar site.

For nearly 2,000 years this church has been waging war on local snakes by importing cats.