Credit: Infophoto/LFI

The entire Jolie-Pitt clan is conquering Venice!

Brad Pitt and Angelina Jolie took their brood -- including the rarely seen twins, Knox and Vivienne, 19 months -- out for a day of fun while in Venice, Italy, on Tuesday.

The family had lunch at a local trattoria with "just simple and rustic food," a source tells

After lunch, Jolie and Pitt took their four older kids -- Maddox, 8, Pax, 6, Zahara, 5, and Shiloh, 3 -- for ice cream, despite the chilly temperatures.

"Angelina took the orders," an onlooker tells Us. "Shiloh had chocolate and vanilla, Pax had passion fruit, Angelina had Vanilla, Zahara had fruit cocktail and chocolate boulles and Maddox got the same."

After a water-taxi ride, they headed home. While getting into a cab, Jolie, 34, carried Vivienne (who kept warm with a white cable-knit cap with a fur-ball on top) and Pitt, 46, carried Knox (who wore a black cap to match his dad's).

It's the first time in months that the twins have been snapped. Knox and Vivienne were last photographed -- by a fan who posted the pic on Twitter -- in October during another ice cream run with their parents in Amman, Jordan.

The brood is staying in the ancient city of canals as Jolie prepares to shoot the film The Tourist in March. The family is renting out a stunning 15th century Palazzo during their stay.