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

A sculpture serving as an homage to Pope John Paul II.

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

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

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

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

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

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

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

The Habsburgs' royal collections of art and wonders.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

The solemn exterior conceals an opulent interior of this 17th century church.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A neo-Gothic mansion now houses a wunderkammer of analog tech that hits on all the senses.

Op-art architecture designed for happiness.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

Museum devoted to the artificial language of Esperanto.

Handsomely crafted representations of our round planet.

An exquisite Baroque church in Vienna's old town.

A silly medieval mural preserved on the side of a Viennese house.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

The final resting place for the remains of 143 Habsburg royalty.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.