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

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

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

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

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

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

The final resting place of the poets Shelley and Keats.

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

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

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

Architectureal fantasy quarter of Rome.

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

An alchemist's "magic door" stands in the middle of a Roman park.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

A terrific purveyor of natural history objects and curios.

A fernery hidden by neglect is uncovered, and an ancient specimen along with it.

This hidden green space is the city's second largest conservatory.

A lakeside garden in the Southern Alps full of whimsical artwork and thousands of beautiful flowers.