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

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

A monumental fountain in Rome features a large statue of Moses that has been criticized for centuries.

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

This sublime architectural marvel is a rare example of an expressionist church.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

Visitors are treated to a stained glass kaleidoscope interior inside this work of art.

The final resting place of the author who gave us the Little Mermaid, the Ugly Duckling, and many more beloved fairy tales.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Copenhagen's celebrated theme park and gardens.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

A sharp sculpture made of thousands of pieces of jagged glass.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

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

Legend says this sacred tree was a gift from goddess Athena.

The site where hundreds of Greeks were tortured by the Nazi secret police is now a cosmetics store.

Where commuters walk through remnants of an ancient Greek necropolis.

An ancient octagonal weather station named for the eight Greek gods of wind.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

150 or so scrounged-up lamps, chandeliers, and lanterns light up this alley in central Athens.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.