Director Gianfranco Rosi celebrates his Golden Lion for the documentary 'Sacro GRA.' (Andrew Medichini/Associated Press)

The Italian film Sacro GRA, a documentary about life along the highway that circles Rome by director Gianfranco Rosi, won the Golden Lion for best film at the 70th edition of the Venice Film Festival on Saturday.

Rosi called the award "a breakthrough" for documentaries, given that this edition marked the first time documentaries were included in the main competition.

"I didn't expect to win such an important prize with a documentary," Rosi said. "Finally documentaries are being seen alongside fiction. Documentaries are cinema."

Rosi dedicated the prize to the characters in the film "who allowed me to enter in their lives. Some of them became involuntary protagonists, without knowing it."

It was the first time an Italian film has won the top prize at Venice in 15 years, when Gianni Amelio won for The Way We Laughed in 1998.

The Silver Lion for best director went to Alexandros Avranas of Greece for Miss Violence, a disturbing look at sexual violence and abuse perpetrated by a grandfather.

Greek actor Themis Panou won the best actor prize for his leading role in Miss Violence, and Italian actress Elena Cotta won best actress for her role in Emma Dante's A Street in Palermo, about two women who reach a standoff when their cars come grill-to-grill in a narrow Sicilian street.

Tye Sheridan, 16, won the best young actor award for his role opposite Nicolas Cage in Joe as a boy who looks to Cage's Joe for guidance as he struggles with an abusive and drunkard father. Sheridan has appeared previously in Terrence Malick's The Tree of Life.

The Grand Jury Prize went to Tsai Ming-liang's Stray Dogs, about a father and two children living on the margins of modern-day Taipei. The director, who won the Golden Lion in 1994 for Vive L'amour, thanked the Venice audiences "that slowed their pace to watch my movie."

Philomena won best screenplay for Steve Coogan and Jeff Pope. The film by Stephen Frears stars Judi Dench in the real-life role of an Irish woman who was forced by nuns to give up her son for adoption, and keeps it secret for nearly 50 years until she sets off on an unlikely journey to the U.S. with a jaded journalist to search for her son. 

The Special Jury Prize went to German director Philip Groening's The Police Officer's Wife, about violence between husband and wife and a mother's efforts to protect their child's innocence.

Oscar-winning director Bernardo Bertolucci headed the nine-member jury that screened 20 movies in competition, and read out the winners from a wheelchair on stage. He told reporters at the start of the festival that he hoped to be "surprised" by the winners.