HBO takes the task of bringing George R.R. Martin’s bestselling epic fantasy series, Game of Thrones, to the small screen quite seriously. Witness: Dozens of staffers sewing and embroidering Medieval-style dresses, hand-crafting chain mail, drying and aging fabric, and hammering armor. A crew member spending an hour meticulously skimming a lagoon before it could serve as the setting for a talk between Lord Eddard Stark (Sean Bean) and his wife, Catelyn (Michelle Fairley) — and this after set designers found the perfect tree in the middle of a Northern Ireland forest, painted it white, and dressed it with red leaves. In pouring rain. In ankle-deep mud.

There’s good reason for the attention to detail. The wildly popular book series — which chronicles the battle for the throne of King Robert Baratheon (Mark Addy) of Westeros and the soapy goings-on among the kingdom and its enemies — boasts legions of obsessed fans, who’ve hung on every detail of HBO’s forthcoming adaptation. They’re the ones most likely to notice that a key scene has moved from Catelyn Stark’s bedroom to a meeting place in the forest or to geek out on the entire new tongue that the Language Creation Society has whipped up just for Dothraki chief Khal Drogo (Jason Momoa) and his countrymen. “It’s better than Klingon,” executive producer D.B. Weiss says. “And you can quote me on that.” EW visited the Belfast set — in the historic Paint Hall Studios — for an exclusive first look at the series. Among the tidbits we uncovered:

* Something for female fans to look forward to: “I lie naked in furs,” Momoa says of his Genghis Khan-like character’s standard operating procedure. “I think I’m naked more than I talk.”

* Weiss and co-showrunner David Benioff first considered Martin’s books for feature film treatment, but “within a week of the time when I finished it, we said we didn’t know how to do this as a movie,” Benioff says. “To do the first book even as a three-hour movie, you’d have to cut 90 percent of it. I’m used to adapting books, and sometimes you have to be ruthless, but in this case we loved all the storylines and the characters. We weren’t interested in that kind of mutilation. So the only way to do this would be as a series.”

* Even non-fantasy fans can get into Thrones, Benioff says, “because it’s not about unicorns and sorcerers. There’s magic in this, but it’s on the fringes.” Quips Weiss, “To be fair, season 2 is going to be all about unicorns. So the characters will all die and be replaced by unicorns. Don’t tell George.” (Note to fans: Seriously, he’s kidding.)

* Speaking of the author, he’s intimately involved in the project: “It’s a lot of late-night emails,” Weiss says. “George watches all the casting videos and tells us who he likes.” Martin was also on set for the pilot as well as for some filming this fall, and he wrote episode 8.

Check out our exclusive sneak peek gallery at ew.com/gameofthrones, and for even more Game of Thrones photos pick up this week’s issue of Entertainment Weekly, on stands Nov. 19.