This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

A curious memento mori hangs in the magnificent Cathedral of Segovia.

This influential Renaissance-era library was once the haunt of kings and monks.

A display of torture devices used in the Spanish Inquisition and other scourges of medieval Europe.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

These sacred Mesoamerican ruins feature peculiar petroglyphs hidden in the stones.

A 500-year-old series of tunnels long believed to be folkloric was uncovered beneath the streets of Puebla.

The splendor of this 17th century golden chapel has led it to be called the "eighth wonder of the world."

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

This strange statue features a bust of the famous composer plopped atop a woman's body.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

These banned cigarette vending machines now sell little pieces of pocket-sized art.

Mausoleums, astronomy, and animatronic dinosaurs at this memorial to an assassinated American president.

A small marionette collection located within the dark cellars of an 11th-century Austrian castle.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

The fairy tale castle of the "fairy-tale king."

This skeleton-filled altar piece served as a backdrop to one of the most iconic scenes in "The Sound of Music."

The prototype for all Nazi concentration camps.

A small but immensely extravagant palace built by the "Night King."