This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A hidden architectural treasure in New York's Brooklyn.

A crumbling hospital from the 1850s on Roosevelt Island.

A massive mausoleum towers over the gravestones in a 19th-century Italian "model village."

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

A Nesting Doll of Churches.

The bones of some 7,000 soldiers killed in the historic Battle of Solferino are stored here.

Sleep amongst an abundance of art from the modern era.

The skulls and bones of thousands of soldiers line the walls of this small Italian chapel.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

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

Architectureal fantasy quarter of Rome.

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

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

A hip bar decorated with walls of golden skulls.

Settled in 1696, abandoned after the Revolutionary War.

One of the oldest living oak trees in the Southeast.

Paths are maintained, but trees have taken over plots.

The signs of a long buried road can still be found hidden beneath a London sewer grate.