The hitman has been prolific for New York City in the MLS and his performances have put him the radar of a number of sides.
He has been mooted as an option for Leeds, where American boss Jesse Marsch keeps close tabs on the MLS, while Nottingham Forest have also been linked with the hitman.
The Argentine striker’s first stop in Europe though could be at Spanish side Girona.
According to MLS-focused journalist Jaime Ojeda, Castellanos favours a switch to Girona, another club owned by the City Football Group.
He is keen to test his mettle in European football and could move to Girona on a season-long loan deal.
Girona won promotion to La Liga last season and will be looking for Castellanos to add goals to their side as they bid to impress in the Spanish top flight.
Castellanos has hit the back of the net 12 times in just 15 MLS games for New York City this season, along with striking on four occasions in six CONCACAF Champions League.
