Mel Gibson and Sean Penn are filming their upcoming movie, The Professor And The Madman, in Dublin.

The film is based on Simon Winchester’s 1998 bestselling novel The Surgeon of Crowthorne. It tells the story of how the Oxford English Dictionary was created.

Both actors aren't strangers to working in Ireland. In 1995, Gibson filmed significant scenes of his best known work, Braveheart, in Wicklow, Kildare, and Meath. Penn also shot the 2010 movie This Must Be the Place, in various locations around Dublin.

The supporting cast includes a heap of young Irish talent including Abigail Coburn, Zoe Moran, Rob McCormack, Phonsie Wardell and Nora Cooper.

The Professor And The Madman will be directed by longtime Gibson collaborator Farhad Safinia, who has worked with Mel on previous projects Apocalypto and The Passion of the Christ.

Meanwhile, the Australian actor will be on our screens very soon indeed with Blood Father, the action thriller which arrives October 7.