Nature offers us some extraordinary wonders, and this time, Alberto Angela takes us to the Frassassi Caves, in the Marches region, and explains what the caves were used for by prehistoric man.

Alberto Angela brings us to the Ancona Abyss, an immense cave chamber in the Natural Regional Park of Gola della Rossa and Frasassi in the Marches region. The spectacular Ancona Abyss and other innermost caves in the Frasassi cave system were only discovered in 1971.

Alberto Angela tells us how these natural wonders were discovered by a group of young cave explorers from the nearby city of Ancona.

Alberto Angela describes the discovery of the Ancona Abyss, named after the city the speleologists were from. It’s part of the Great Wind Cave.

The magical Frasassi caves look like something out of a fairy tale, but there's a more scientific explanation.

Alberto Angela tells us how these caves and their internal structures were created. The key is something very simple. Water.

We spend some more time in the spectacular Frasassi Caves, and this time we see the famous "Room of the Candles" filled with stalagmites that look like candles ready to be lit. Alberto Angela also discusses the colors in this place, as well as the "sounds of silence."

The Great Cave of the Wind in Frasassi is a natural wonder, but it also bears witness to the passing of time. Speologists are still exploring it and discovering new wonders.

The Castle of Roccascalegna stands on a high, rocky bluff dominating the valley of Rio Secco in the province of Chieti. Breathtaking drone footage allows us a bird's eye view of this fascinating construction, begun by the Lombards as a watchtower.

We are back visiting nature's own wonders, this time up in the mountains, on Mont Blanc, to be precise, at an altitude of over 4000 meters.

Mont Blanc has always been considered the highest peak in Europe. But is it? Alberto Angela discusses this and another question: What's the real height of Mont Blanc and why do they have to measure it every two years?

We learn about the curious names of some of Mont Blanc's magnificent peaks and glaciers. Normally there are 42 glaciers but that number can change!

We move to the French side of Mont Blanc, which has a much milder slope than the Italian side. Mont Blanc stands out as having had an important role in the development of mountain-climbing as a competitive sport.

One reason people would climb Mont Blanc was to find quartz. Alberto Angela explains why there is so much of this precious gemstone here.

Alberto Angela talks about how Mont Blanc was formed over millennia, and concludes this episode with a breathtaking view, as well as some lines from a poem by Shelley. Here is the original English:
Far, far above, piercing the infinite sky,
Mont Blanc appears,—still, snowy, and serene—
In the calm darkness of the moonless nights,
In the lone glare of day, the snows descend
Upon that Mountain;
[Nor when] the flakes burn in the sinking sun,
[Or] the star-beams dart through them:—Winds contend
Silently there, and heap the snow with breath
Rapid and strong, but silently! Its home