Jesus' footprints and the first catacombs in the world.

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

This house was the subject of an Edward Hopper painting, which in turn helped inspire the design of the Bates house in Alfred Hitchcock's 'Psycho.'

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The oldest operating pharmacy in the world features 800-year-old recipes.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Its interior is adorned with some of the best examples of early Christian mosaics.

The ruins of an abbey believed to have been founded by Charlemagne in the 9th century.

A Nesting Doll of Churches.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

This beautiful Romanesque church preserves stunning medieval frescoes and the excavations of a Roman market town.

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

The grotto where Saint Ignatius of Loyola lived as a hermit for nearly a year.

This medieval church is the only one in the world that features all Marc Chagall stained-glass windows.

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

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

A Byzantine-era church hidden in a wooded area below the Acropolis.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

Originally envisioned by King Ludwig II to rival Versailles, Herrenchiemsee's "New Palace" remains half-gilded for lack of funds.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.

This 8th-century Bavarian monastery is home to an exquisite Baroque-era library.

When a medieval fire claimed the original St. Stephen’s Cathedral, it sparked a pattern of unquenchable organ building.

This Rococo church is known as the most beautiful village church in the world, and does not disappoint.