Sick and tired of the sweltering heat in the city, the woman decided to refresh herself in the beautiful Fountain of the Naiads, in Piazza della Repubblica, Il Messaggero reported.
But as she splashed about, she was watched by a police officer who was directing traffic around the square.
And as the police officer looked on, Sergio Mattarella drove by with a full presidential escort.
Who knows what the Italian president made of the bather, or the police's failure to intervene - but by now such sights are commonplace in the Roman capital.
So common in fact, that fines have increased from €160 to €500 for anyone caught taking a sneaky dip.
The new maxi-fine was launched by under-fire Rome mayor, Ignazio Marino, as part of “Operation Clean Fountains” on Tuesday. But that clearly wasn't enough to dissuade the woman.