Songfacts®:

• The title track from Lissie's fourth studio album started out as a love song about finding the ideal romantic partner but evolved into something more. She explained in a track-by-track commentary: "I love 'Castles' because it's a romance song, an idealized song about romance. These two equals show up and together are really able to run their kingdom in this really healthy, beautiful way. One thing I discovered in 'Castles' is originally it was a song about love, but then the more I listened to it, as I look at the world around me and I listen to the news, it's more than just romantic love. I think it's a song about unifying people in a way, too, like, 'wouldn't it be good if we could rule together and love the way we should' - if in society our leaders could be cooperative and communicative and reasonable. 'Castles' is my kingdom so it could be a utopia where we all figure out how to share the Earth's resources and respect them so that we can all have a good life. But then it's all about finding the partner that can sort of be the equal I'm looking to find."
• With its hip-hop-style synth beats, this is a sonic departure for Lissie, whose earlier work was built on acoustic and electric guitars and the occasional piano. Surprisingly, the urban sound emerged when Lissie moved from California to a farm in Iowa. "You would think that being on a farm, it'd be like picking a banjo on the porch," she told Songfacts in 2019. "Actually, I experimented a lot more with tracks and beats and meaty synths and stuff because I was so remote. I was living out in the country and I wanted to be home, so people would bring a portable studio to me and that led to me experimenting more with digital instrumentation, whereas in the past it had always been live instruments. So, ironically, moving to a farm made me put more technology into my songwriting. Just out of necessity and convenience because what I was making, I was enjoying, so I went with it. You can tell Castles has a little bit more of that synth bass sound to it because a lot of ideas were kind of hatched there."
• A piano-vocal version is featured on Lissie's 2019 album, When I'm Alone: The Piano Retrospective.