This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

Venice's island of the dead.

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

Go inside to really appreciate this 500-year-old technological masterpiece.

An Italian hillside ghost town.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

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

Venice's "Island of the Mad."

Thousands of well-dressed mummies below a monastery.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

The top of society once luxuriated in this world-class hotel, which continues to impress, even in ruin.

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

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

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

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

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

A Nesting Doll of Churches.