Despite the downpour and difficult conditions underfoot, Cardiff - who knew their place in next year's Heineken Cup was secure before kick-off against the Italians - looked impressive and also saw Rhys Patchell and Gavin Evans go over.
But the day belonged to 26-year-old Roberts, who had the chance to offload but wanted to mark the occasion in his own special way.
"I wasn't going to pass," said Roberts. "It was great to score the last try as it is something to remember of the famous old ground.
And head coach Phil Davies added: "The conditions were tough and the pitch has been an issue for some time.
"We played the game in the right areas but didn't convert as many opportunities as we would have liked."
63x46.png){kind=logo}