Castan has confirmed he's joining the Giallorossi.
"I'm joining Roma to take a step forward in my career, but I know that it will not be easy," stated the 25-year-old.
"It will be an important opportunity for me. I will be playing at the highest level, but I think I can do that well.
"Serie A is a strong championship, but I hope that I will be able to play in the Europa League and Champions League while I am there."