The celebrated eyesore created by starry-eyed sweethearts.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This bridge was constructed from the rubble of the infamous Bastille.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

Paris' linguistic guide to the international language of, yes, love.

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

Site of a classic 19th-century physics experiment to prove the earth is rotating.

A 12th-century Italian skirmish gets reenacted with 500,000 pounds of flying citrus.

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

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

These spartan apartments are provided to clergymen visiting Vatican City.

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

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

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

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

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

Gods clash with machines in a power plant regenerated as a museum.

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

Rome’s legendary peephole vista is also a former Crusader stronghold.

The final resting place of the poets Shelley and Keats.

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

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

A Nesting Doll of Churches.