Heading south, we cross Europe's cultural and geographical divide, driving from the Germanic world, over the Alps, into the Mediterranean world — Italy. The Brenner Pass has been the easiest way over the Alps since ancient Roman times. Two thousand years ago, Roman legions followed this route — the Via Claudia — as they marched north to conquer much of Europe.

Sections of the ancient road are still preserved. Deep grooves are reminders of countless wagon wheels that followed this very route.

Today, the Brenner Pass is easier than ever to cross, as drivers arc gracefully along one of the engineering wonders of Europe. From the top of the Europabrücke, or Europe's Bridge, it feels like just another freeway, but from the windy old road at the valley floor it looks like a mighty sculpture.

The freeway zips drivers from Innsbruck to the Italian border in about 30 minutes. How about pasta for lunch?

While the autobahn in Germany and Austria is toll-free, the Italian autostrada has plenty of toll booths.

But that's nothing new here. This crossing has long been a gauntlet of toll booths and forts. Empires from Roman times to World War II understood the strategic value of [the] Brenner Pass. This fortress, called "Franzensfeste," was built in the 1830s. It was one of the mightiest of its day. A huge investment by the Habsburg emperor in Vienna, it was designed to protect his empire from invasions from the south.

Throughout the Middle Ages, this was the trade route that connected the Germanic world with cities like Venice and Florence. When medieval traders reached this valley, chances are they were stopped, willingly or not, at a castle like this. Reifenstein Castle was built to control trade. But Reifenstein has grown more welcoming with age. While it used to take a battering ram to get these doors open, now all it takes is a few euros.

Caretaker: Hello, hello.
Rick: Hey — guten Tag.
Caretaker: Welcome to Reifenstein.

Reifenstein offers one of Europe's most intimate looks at medieval castle life. The actual count and countess of Reifenstein are determined to preserve their historic castle. The castle caretaker shows visitors around on tours several times a day. We're enjoying a private visit.

While the castle was originally built a thousand years ago, what we see today is about 500 years old. It's a rare opportunity to see an intact medieval castle interior. Within its mighty stone walls, hefty timbers flesh out the staircases and rooms. The woodwork is artful, and the engineering ingenious.

While there was no well, rainwater was collected into a cistern that functions to this day. Paintings adorning the walls feature only one family: the noble German family that has owned the castle for centuries. Here the lord and lady seem proud of what must have been an impressive fortified home in its day.

Here's a fun fix for a tipsy lord. Too much to drink? A clever funnel guides the key right into the hole.

From the looks of the sumptuous green room, medieval life for the nobility was pretty comfortable. The painted walls are original — a rare example of secular art surviving from the Middle Ages. With voluptuous swoops and curls, this scene, frescoed in 1498, is a fantasy of elves, jesters, archers, and fruity symbols of fertility.

You can catch a view across the valley to Reifenstein's sister castle. Two castles like these, strategically straddling the valley, could control much of the trade passing between Germany and Italy.

To exercise his power and collect those tolls, the castle lord needed a small personal army. This room is the knights' quarters. Up to eight men shared each of these boxes — complete with hay, for maximum comfort. Imagine 40 snoring knights packed into one room. There was no fire for warmth, as an accident would set the entire place up in flames. So, the knights huddled together to stay warm.

And every good castle needs a dungeon, used mostly to enforce the payment of debts. The only way in or out was through this hatch. If you couldn't pay your bills, you could spend days down here — no food; only a little water.