HBO has greenlighted "Game of Thrones," an epic fantasy series based on author George R.R. Martins bestselling novels.

Set to debut next spring, Game of Thrones will feature 10 episodes, and will span a novels worth of material per season. Production is scheduled to start in Northern Ireland in June.

HBO completed the pilot in November, reportedly spending between $5 million and $10 million on the production. Last month, network executives previewed a rough cut and were impressed enough to issue a greenlight.

"Everything looks fantastic," said Michael Lombardo, HBO's programming chief. "The director got great performances. Unlike a lot of projects like this, everything was shot on location. It has such a rich texture that it looks more expensive than it actually was."

One of the show's selling points for HBO was its adult tone, reminiscent of their acclaimed series "Deadwood" and "Rome."

"You forget it's fantasy while you're watching it, and that's what I love about it," Lombardo explained.

Tom McCarthy, who earned accolades for his work on 2003's "The Station Agent" and 2007's "The Visitor," directed the pilot based on a script penned by the show's executive producers David Benioff ("Troy," "The Kite Runner") and D.B. Weiss.

McCarthy's involvement past the pilot has yet to be confirmed.

With "Game of Thrones" earning a greenlight, casting for Season 1 is expected to ramp up soon. Already aboard the series are Sean Bean ("The Lord of the Rings"), as Eddard "Ned" Stark; Lena Headey ("Terminator: The Sarah Connor Chronicles," "300"), as Queen Cersei Lannister; Peter Dinklage as her cunning dwarf brother Tyrion; Nikolaj Coster-Waldau ("New Amsterdam") as her twin, Jaime; Jennifer Ehle as Ned's wife Catelyn Stark; and Mark Addy as King Robert Baratheon.

Based on Martin's A Song of Ice and Fire series, the books follow the treacherous clash between royal families to secure ultimate power of the vast lands of Westeros. Royalty and knights play a perilous game of intrigue, where those gifted with unflinching resolve and a keen eye for subterfuge often conquer more than the greatest armies.

The novel "A Game of Thrones" quickly won readers over when it hit the shelves in 1996, later winning the 1997 Locus Award, and receiving nominations for both the 1997 World Fantasy Award and the 1998 Nebula Award. More awards followed for subsequent books in the series. Seven novels are planned, with the fourth volume, "A Feast For Crows," being the latest.

Check out the first official photo from the production below. It features a look at the pilot's opening scene.