Italy's Invisible Cities

In episode two, Alexander and Michael take to the canals to discover the hidden secrets behind one of the world's most remarkable cities - Venice.

Beginning their journey in Saint Mark's Square, Alexander and Michael take in the fusion of cultures in the buildings around them. They re-join the scanning team to hear how they will create a millimetre-accurate digital map of Venice, starting with Saint Mark's Cathedral (pictured). Using new technologies, the team will build an innovative and interactive snapshot of Venice that can be used to help monitor and conserve this crumbling city.

To complete the picture, Michael dives into Venice's notoriously dirty canals to find out how the city remains standing despite its watery foundations. Exposing load-bearing wooden piles preserved in mud, Michael explains the ever-present danger to the city's stability from the boats and rising waters.

Venice's numerous bridges connect busy streets and piazzas. Michael and Alexander visit the famous Rialto Bridge to see how this magnificent piece of architecture hides engineering genius in its foundations. The scanning team is on hand to reveal the secrets in detail.

Using 3D scans to uncover hidden jewels in the Jewish Ghetto and the endless passageways inside the Doge's Palace, Michael and Alexander finish their visit with an exploration of the history of Venetian sin and pleasure. Writer Tony Perrottet gives Alexander a tour of one of Venice's historic gambling houses, frequented by cliental such as Casanova. Casanova knew the dark side of this city first hand. Michael and Alexander visit a hidden network of rooms in Doge's Palace, including the torture chamber where Casanova was interrogated. With the help of 3D recreations of the Doge's Palace, Casanova's escape route is re-traced in virtual reality.