This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

Climb inside an iron crystal magnified 165 billion times its normal size.

Atop this former dutch railway office sits an interstellar work of art.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

It appears as if a man is standing behind this giant airport clock, painting the hands in real time.

A miniature city, once ruled by the Queen of the Netherlands.

Amsterdam's former hotspot for public executions and dissections.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

This unattributed sculpture in Amsterdam is hiding in plain sight.

The attic of a four-century-old canal house hides a clandestine church.

A statue representing a lost Roman profession that was vandalized for centuries.

Romans decided this 16th-century "talking statue" was so ugly, they named it after a primate.

A fortified medieval basilica on the Caelian Hill preserves extraordinary frescoes and one of Rome's most beautiful hidden cloisters.

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

A rather vulgar example of the transition from Latin to the Italian vernacular.

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

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