Robert Pattinson is celebrating his 25th birthday today (13.05.11).

The 'Twilight' hunk is said to be spending his special day with his rumoured girlfriend and costar Kristen Stewart in Toronto before he starts shooting his next film 'Cosmopolis'.

He will star opposite Canadian actress Sarah Gadon in the film, which tells the story of a young businessman who bets all of his money, only to find himself at the centre of an assassination plot.

Robert - who is currently starring in 'Water For Elephants' with Reese Witherspoon - is likely to enjoy a loved-up birthday with Kristen and recently revealed how much he enjoys being in a relationship.

Asked if he is romantic, he said: "I guess I am when I like someone, I like being in love with people and yes, I guess I am quite sensitive to things.

"It's important to preserve any mystique you have and also I just don't feel it's anyone else's business."