Wall, who had never heard of Martin’s original book series, was brought in a year before the show was set to debut. He began by meeting with the Thrones brain trust, including Strauss, show creators David Benioff and D.B. Weiss, and producer Greg Spence. Originally, the pilot script included the description of a proposed title sequence: “A journey of a raven from, I think, Winterfell to King’s Landing,” Wall recalled. “We created some concept art for that, which was actually really promising and really beautiful.”

But as Wall and his team of collaborators (including art director Rob Feng and designer Hameed Shaukat) realized, ravens flying from one fictional place to another might be slightly disorienting for viewers new to the world of Thrones. They scrapped the raven idea, instead brainstorming a title sequence that would serve as a basic introduction to Martin’s fantasy world. This was around the time C.G. supervisor Kirk Shintani came on board, helping the team conceptualize their new idea: a sprawling map of the realm.

“The first trick was, how do you make a map without making a map?” Shintani said. “We really wanted to avoid doing the cliché, flat, parchment kind of look, you know? So for us, the trick was, how do you get rid of the horizon line?”

Their solution was to make the map its own insular world, dotted with eye-popping fixtures—like castles and the Wall—that could jut up from the ground, creating a steampunk-meets–da Vinci aesthetic. To further tie their creation to Martin’s universe, their vision drew upon “the same materials that you would find in the show itself: metal, some leather, wood, glass,” Wall said. “Really basic materials that could have a very elaborate, sort of mechanized set of gears driving them.”

Though it looks rough-hewn, the sequence was created entirely digitally—all the better to include nods and references only the most die-hard fans would spot. “All the engravings on the astrolabe itself, those actually tell a backstory and prehistory to Season 1,” Shintani noted.

Speaking of that instrument: in Season 6, the character Samwell Tarly travels to the Citadel to become a maester and, while there, sees a massive astrolabe. The sight of it sparked a theory among fans: is the show being told from the point of view of a maester (perhaps Sam himself) in the future? There are other hints in the show that support this theory as well. One maester at the Citadel, for example, wears a thick pair of glasses. At certain points in the show’s title sequence, it appears as though the map is being viewed through those thick lenses.

“I love that theory,” said Wall. “One of the things that we jokingly talked about in the beginning was, we were creating a map that a bunch of mad monks were watching as the show’s narrative unfolded. It was a way to sort of globally view everything that’s happening, so it’s good that [fans] came up with that, however misguided.”

“When I came across that one, I thought it was pretty awesome,” added Shintani, who noted that Thrones’ production team asked them to collaborate on the astrolabe shown in that Season 6 episode. “We were thrilled. For us, it kind of bridged the gap between our map and the actual show itself.”

Eagle-eyed fans have also noticed other, more N.S.F.W. things about the title sequence. Look closely at the left-hand side of the astrolabe band at the 1:27 mark, and you’ll see a sigil of a boar (for House Crakehall) and a bear (House Mormont). Because of the way they’re positioned, it looks like the bear is, well, doing something very suggestive with the boar.