Although it seems hard to believe, Game of Thrones has almost entirely caught up with George R.R. Martin’s novels in just five seasons. But there are a few things the show hasn’t yet really explored, and a very interesting new location for Season 6 might confirm a pretty huge theory fans have had for a long time.

This past week, HBO announced some new locations for Season 6, including the Castillo de Zafra in Guadalajara (hat tip to Watchers on the Wall). The castle is of particular note to fans of A Song of Ice and Fire, who have long hoped for the inclusion of the Tower of Joy along with flashbacks that could confirm a big fan theory.

It’s yet to be confirmed by HBO, but given the evidence we have thus far, it seems very likely that the Castillo de Zafra will be used as the Tower of Joy location in Season 6.

For those unfamiliar, the most popular fan theory based on A Song of Ice and Fire is known as “R+L=J.” When Ned Stark is called to his dying sister Lyanna at the Tower of Joy, he finds her in a bed of blood and she asks her brother to make a solemn vow. The particulars of that promise are never revealed to the reader, but many have developed the theory that Lyanna was bleeding following a harrowing childbirth, and that the promise Ned makes is to take care of her newborn child — that child being the result of a union between Lyanna and Rhaegar Targaryen, who kidnapped Ned’s sister away from her intended husband, Robert Baratheon, inciting a war between the two.

As the theory goes, the child Lyanna may have given birth to is Jon Snow, Ned’s bastard son whom he raised as his own at Winterfell. Given what we know about Ned’s morals from both the series and the books, it seems hard to believe that he ever stepped out on Lady Catelyn, and with how devoted we know he was to Lyanna, his similarly intense devotion to Jon Snow makes even more sense in this context.

In addition, a recent casting call for Game of Thrones Season 6 asked for an actor to play a “legendary fighter,” known as a “paragon of knighthood.” Fans have speculated that this is the role of Ser Arthur Dayne, whom Ned Stark believed to be the best knight who ever lived. Dayne was guarding the Tower of Joy when Lyanna died.

All of this appears to suggest that Season 6 will contain one (or a few) flashbacks further clarifying Stark history as well as possibly confirming the R+L=J theory. Showrunners David Benioff and D.B. Weiss reportedly landed the Game of Thrones gig because they correctly guessed the identity of Jon Snow’s mother, and their work on the series has in some ways supported the fan theory.

And if we’re getting a Tower of Joy flashback in Season 6, this does little to discourage the rumors of Jon Snow’s return — why incorporate this particular origin story if he’s truly deader than dead? Although the series is mostly caught up with the books, there are ways for Jon Snow to return (Melisandre, Thoros of Myr, etc.), and we can now add this Tower of Joy location to the huge pile of evidence that suggests the showrunners are lying about the permanence of Jon Snow’s death.