Well here:-
http://blog.arduino.cc/2014/05/24/maker-faire-rome-takes-off/#more-9525
It says:-
So, we have the names. Now, where will they all be? This is the second novelty: we will leave the Palazzo dei congressi and, instead, meet at the Parco della Musica designed by Renzo Piano. Not only is it the most beautiful structure for events in Rome, it is a real park where we intend to build a Makers Village comparable to those that exist in San Mateo and New York.
Which sounds to me like it is all booked up.
It is also the venue for the open hardware summit two days before.