Not long after Rogue One: A Star Wars Story hit theaters, many fans had questions about a certain location we see in the movie that isn’t identified with any on-screen text. There’s a certain scene that takes place in a castle inhabited by Darth Vader. We’ve already learned some details about the location, including confirmation that it can be found on the volcanic planet Mustafar and the fact that it’s built on top of a Sith cave. Now even more information has come to light.

Rogue One co-production designer Doug Chiang recently sat down for an interview to discuss the work he did on the Star Wars spin-off, and part of the extensive discussion included Darth Vader’s castle details that are rather intriguing.

Over at StarWars.com, Doug Chiang talks at great length about the work he did on Rogue One, but this stuff about Darth Vader’s castle contains some of the more interesting information, showing just how much thought goes into creating a location like this in the Star Wars universe.

Chiang explains that Darth Vader doesn’t just live in a castle surrounded by lava because it looks cool. There’s real motivation as to why Vader lives here, and a lot of it actually has to deal with what happened on Mustafar with his old mentor, Obi-Wan Kenobi. The co-production designer explains:

“The initial idea was, ‘Why would Vader live here?’ In our minds, we started to come up with a little bit of a backstory. That perhaps this place had special meaning for him, and that this is where he comes to meditate and to heal himself. We started with the idea that maybe it should be built around his bacta tank chamber, and he comes back here to rejuvenate himself and also to meditate. So from there, the structure itself grew out from the bacta tank, and there were certain ideas that we tried.”

Beyond the location of the castle, even the design itself serves a practical function for the Sith. Chiang continues:

“We were trying to go for a very iconic shape, and we always love tall towers. Ralph McQuarrie actually drew quite a few small thumbnail sketches [of Vader’s castle] that were very intriguing. They were kind of angular versions of a tower, and I saw the potential of where he was going, and I just exaggerated that quite a bit. One of things we landed on early was this idea of a tuning fork — a twin tower kind of look. And it was really interesting, because then that started to give Gareth a lot of ideas like, ‘Well, maybe the structure is built this way because it is like a tuning fork. It’s tuning the dark side in terms of the energy.'”

As we covered in our first relay of details about Darth Vader’s castle, The Art of Rogue One book indicates that there may be a Sith cave found underneath the castle, which would explain the tuning fork design. But beyond that, there are even more ancient parts of the castle. Chiang says they went back to the idea of just why Vader would be here, inspired by images from unused concept art images by Ralph McQuarrie where Luke Skywalker visits Vader in an underground lava cave. He elaborates:

“I always thought that was such a compelling image, because you have this lava lake inside this cave and there was Vader’s throne. So we took that idea and thought, “Okay, well, maybe on the lower levels of Vader’s castle, there’s a more ancient part. That he actually built this castle on a foundation of an ancient structure.” If you look at the finished design, it has this very strong element of a structure that was there for a purpose, and that purpose was to draw energy from the lava lake. If you look at the design of the base, it feels very much like a dam, and how the lava flows through it, possibly getting energy. And so we thought, “Okay, well, that’s the foundation. Maybe even deeper, or underneath that, is an even more ancient part, which is a natural cave where Vader goes to meditate.” Visually, we’re trying to create a sort of history for the tower. The bottom is the most ancient, the lava lake dam part was perhaps what Vader built his foundation on, and then the tower was Vader’s addition.”

That’s a lot of thought going into a location that appears on screen for a matter of minutes. But when it’s the home of the most notorious Star Wars villain, you really have to make sure that every details is planned meticulously. This is something that is now canon for the entire franchise, something that can be used and referenced in countless other stories, so it needs to be created with logistics and practicality in mind.

Is there a chance introducing a structure such as this into Star Wars canon could come into play later somehow? After all, we know that Luke Skywalker went to go find the first Jedi temple when he disappeared after Return of the Jedi. Is there a chance Kylo Ren could maybe go looking for answers at his grandfather’s home one day? We’ll have to wait and see. In the meantime, check out the whole interview with Doug Chiang over at StarWars.com, and read out previous piece on Darth Vader’s castle right here.