A forgotten "city of water" underneath the famous Trevi district.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

One of the most important yet well-hidden museums dedicated to the history of medicine.

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

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

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

A hospital where antique dolls are given new life.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

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

A collection of objects supposedly singed by the hands of souls in purgatory.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Architectural monsters are devouring this palace's every door and window.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

This long-hidden space above Westminster Abbey now displays the battle gear of the legendary King Henry V.

These morbid carvings remind churchgoers of the inevitability of death.

Eclectic final resting place of the controversial explorer.

A Roman spa buried deep beneath the City of London.

A naturally mummified 2,000-year-old man.

Scattered throughout London are ancient remnants of the city's former bounding wall.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

A cluttered and astounding collection of antiquities and curiosities.

The final resting place to 300 Victorian-era pets hides inside the city park.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.